A087203 - OEIS

A087203

a(n) is the smallest m such that m > A037155(n) and n!- m is prime.

4, 7, 11, 19, 19, 37, 17, 17, 17, 17, 61, 43, 59, 71, 61, 43, 113, 71, 41, 101, 191, 103, 191, 179, 71, 127, 37, 97, 113, 373, 71, 373, 293, 157, 149, 241, 167, 211, 151, 89, 131, 113, 73, 107, 179, 227, 173, 113, 257, 239, 151, 227, 163, 509, 293, 347, 643, 373, 457

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OFFSET

3,1

COMMENTS

a(1) and a(2) are not defined. a(n) is the second m (first m is A037155(n)) such that m > 1 and n!- m is prime.For 3 < n < 643,a(n) is prime. I guess (compare the conjecture about A087202) except for the first term, every term of this sequence is prime.

LINKS

Table of n, a(n) for n=3..61.

FORMULA

A037155[3]=3; A037155[n_] := (For[m=Prime[PrimePi[n]+1], !PrimeQ[n!-m], m++ ]; m); a[n_] := (For[m=A037155[n]+1, !PrimeQ[n!-m], m++ ]; m)

MATHEMATICA

A037155[3]=3; A037155[n_] := (For[m=Prime[PrimePi[n]+1], !PrimeQ[n!-m], m++ ]; m); a[n_] := (For[m=A037155[n]+1, !PrimeQ[n!-m], m++ ]; m); Table[a[n], {n, 3, 62}]

CROSSREFS

Cf. A037155, A087201, A087202.

Sequence in context: A274286 A024882 A296551 * A310768 A109328 A228079

Adjacent sequences: A087200 A087201 A087202 * A087204 A087205 A087206

KEYWORD

nonn

AUTHOR

Farideh Firoozbakht, Sep 01 2003

STATUS

approved