A154302 - OEIS

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A154302

Primes of the form (1+2+...+m)/87 = A000217(m)/87.

5, 19, 43, 173

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Original definition: "Primes of the form : 1/x+2/x+3/x+4/x+5/x+6/x+7/x+..., x=87."

The corresponding m-values are m=29,57,86,173. It is clear that for m>2*87, T(m)/87 = m(m+1)/174 cannot be a prime, since then each factor in the numerator is larger than the denominator. See A154304 for further comments and PARI code. - M. F. Hasler, Jan 06 2013

LINKS

Table of n, a(n) for n=1..4.

MATHEMATICA

lst={}; s=0; Do[s+=n/87; If[Floor[s]==s, If[PrimeQ[s], AppendTo[lst, s]]], {n, 0, 4*9!}]; lst

PROG

(PARI) d=87*2; for(m=1, 999, (m^2+m)%d==0&isprime((m^2+m)/d)&print1(m", ")) \\ print the m-values(!) - use A154304(87) to get A154302 as a vector. \\ - M. F. Hasler, Jan 06 2013

CROSSREFS

Cf. A057570, A154293, A154296 - A154304.

Sequence in context: A172043 A146616 A146395 * A146736 A176358 A045458

Adjacent sequences: A154299 A154300 A154301 * A154303 A154304 A154305

KEYWORD

nonn,fini,full,easy,bref

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jan 06 2009

EXTENSIONS

Edited by M. F. Hasler, Jan 06 2013

STATUS

approved