Displaying 1-10 of 17 results found.
Numbers k such that (k!-4)/4 is prime.
+10
20
4, 5, 6, 7, 8, 10, 15, 18, 23, 157, 165, 183, 184, 362, 611, 908, 2940, 6875, 9446, 16041
COMMENTS
Numbers k such that (k!-m)/m is prime:
for m=2 prime or pseudoprime see A082671
MATHEMATICA
a = {}; Do[If[PrimeQ[(n! - 4)/4], Print[a]; AppendTo[a, n]], {n, 1, 184}]; a (*Artur Jasinski*)
CROSSREFS
Cf. n!/m-1 is a prime: A002982, A082671, A139056, A139199- A139205; n!/m+1 is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A137390, A139071 (1<=m<=10).
Numbers k such that (k!-10)/10 is prime.
+10
20
5, 6, 7, 11, 13, 17, 28, 81, 87, 433, 640, 647, 798, 1026, 1216, 1277, 3825, 6684
MATHEMATICA
a = {}; Do[If[PrimeQ[(n! - 10)/10], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a (*Artur Jasinski*)
Select[Range[700], PrimeQ[(#!-10)/10]&] (* Harvey P. Dale, Feb 15 2015 *)
CROSSREFS
Cf. n!/m-1 is a prime: A002982, A082671, A139056, A139199- A139205; n!/m+1 is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A137390, A139071 (1<=m<=10).
1, 5, 119, 5039, 39916799, 6227020799, 355687428095999, 121645100408831999, 25852016738884976639999, 8841761993739701954543615999999, 8222838654177922817725562879999999, 13763753091226345046315979581580902399999999, 33452526613163807108170062053440751665151999999999, 60415263063373835637355132068513997507264511999999999, 258623241511168180642964355153611979969197632389119999999999, 4274883284060025564298013753389399649690343788366813724671999999999999, 138683118545689835737939019720389406345902876772687432540821294940159999999999999
COMMENTS
Numbers of the form (prime(n)!-m)/m :
MATHEMATICA
Table[(Prime[n]! - 1)/1, {n, 1, 20}]
PROG
(Magma) [(Factorial(NthPrime(n))-1): n in [1..20]]; // Vincenzo Librandi, Jun 02 2017
Natural numbers of the form (prime(n)!-3)/3.
+10
19
1, 39, 1679, 13305599, 2075673599, 118562476031999, 40548366802943999, 8617338912961658879999, 2947253997913233984847871999999, 2740946218059307605908520959999999, 4587917697075448348771993193860300799999999, 11150842204387935702723354017813583888383999999999, 20138421021124611879118377356171332502421503999999999, 86207747170389393547654785051203993323065877463039999999999, 1424961094686675188099337917796466549896781262788937908223999999999999
MATHEMATICA
Table[(Prime[n]! - 3)/3, {n, 2, 20}]
0, 2, 59, 2519, 19958399, 3113510399, 177843714047999, 60822550204415999, 12926008369442488319999, 4420880996869850977271807999999, 4111419327088961408862781439999999, 6881876545613172523157989790790451199999999, 16726263306581903554085031026720375832575999999999, 30207631531686917818677566034256998753632255999999999, 129311620755584090321482177576805989984598816194559999999999, 2137441642030012782149006876694699824845171894183406862335999999999999
MATHEMATICA
Table[(Prime[n]! - 2)/2, {n, 1, 20}]
a(n) = (prime(n)! - 4)/4.
+10
18
29, 1259, 9979199, 1556755199, 88921857023999, 30411275102207999, 6463004184721244159999, 2210440498434925488635903999999, 2055709663544480704431390719999999, 3440938272806586261578994895395225599999999, 8363131653290951777042515513360187916287999999999, 15103815765843458909338783017128499376816127999999999, 64655810377792045160741088788402994992299408097279999999999, 1068720821015006391074503438347349912422585947091703431167999999999999
MATHEMATICA
Table[(Prime[n]! - 4)/4, {n, 3, 20}]
PROG
(Magma) [(Factorial(NthPrime(n))-4)/4: n in [3..20]]; // Vincenzo Librandi, Jun 02 2017
(PARI) a(n) = (prime(n)!-4)/4;
lista(nn) = for (n=3, nn, print1(a(n), ", ")); \\ Michel Marcus, Feb 17 2018
Natural numbers of the form (prime(n)! - 5)/5.
+10
18
23, 1007, 7983359, 1245404159, 71137485619199, 24329020081766399, 5170403347776995327999, 1768352398747940390908723199999, 1644567730835584563545112575999999
MATHEMATICA
Table[(Prime[n]! - 5)/5, {n, 3, 20}]
Natural numbers of the form (prime(n)!-6)/6.
+10
18
0, 19, 839, 6652799, 1037836799, 59281238015999, 20274183401471999, 4308669456480829439999, 1473626998956616992423935999999, 1370473109029653802954260479999999
MATHEMATICA
Table[(Prime[n]! - 6)/6, {n, 2, 20}]
719, 5702399, 889574399, 50812489727999, 17377871486975999, 3693145248412139519999, 1263108856248528850649087999999, 1174691236311131831103651839999999, 1966250441603763578045139940225843199999999
COMMENTS
Not an integer for n < 4.
MATHEMATICA
Table[(Prime[n]! - 7)/7, {n, 4, 20}]
14, 629, 4989599, 778377599, 44460928511999, 15205637551103999, 3231502092360622079999, 1105220249217462744317951999999, 1027854831772240352215695359999999, 1720469136403293130789497447697612799999999
MATHEMATICA
Table[(Prime[n]! - 8)/8, {n, 3, 20}]
CROSSREFS
Cf. A039716, A139189, A139190, A139191, A139192, A139193, A139194, A139195, A139196, A139197, A139198.
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