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A103153 a(n) = smallest odd prime p such that 2*n+1 = 2*p + A000040(k) for some k>1, or 0 if no such prime exists. 8
0, 0, 0, 3, 3, 3, 5, 3, 3, 5, 3, 3, 5, 3, 7, 5, 3, 3, 5, 5, 3, 7, 3, 3, 5, 3, 7, 5, 3, 7, 5, 3, 3, 5, 5, 3, 7, 3, 3, 5, 5, 3, 7, 3, 19, 5, 3, 7, 5, 11, 3, 11, 3, 3, 5, 3, 3, 5, 3, 7, 5, 11, 7, 11, 11, 3, 11, 3, 13, 5, 3, 3, 5, 5, 7, 7, 3, 3, 5, 5, 3, 7, 5, 3, 7, 3, 13, 5, 3, 7, 5, 3, 3, 5, 5, 7, 7, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..98.

EXAMPLE

For n < 4 there are no such primes, thus a(1)-a(3)=0. For n=4, 2*4+1 = 9 = 2*3+3, thus a(4)=3. For n=7, 2*7+1 = 15 = 2*5+5, thus a(7)=7.

MATHEMATICA

Do[m = 3; While[ ! (PrimeQ[m] && ((n - 2*m) > 2) && PrimeQ[n - 2*m]), m = m + 2]; Print[m], {n, 9, 299, 2}]

PROG

(Scheme:) (define (A103153 n) (let ((ind (A103507 n))) (if (zero? ind) 0 (A000040 ind))))

CROSSREFS

a(n)=0 if A103507(n)=0, otherwise A000040(A103507(n)). Cf. A103151, A103152, A002373.

Cf. A195352 (similar definition, but p=2 is allowed).

Sequence in context: A049613 A002373 A236569 * A162022 A318240 A262289

Adjacent sequences:  A103150 A103151 A103152 * A103154 A103155 A103156

KEYWORD

nonn

AUTHOR

Lei Zhou, Feb 09 2005

EXTENSIONS

Edited and Scheme code added by Antti Karttunen, Jun 19 2007

Definition corrected by Hugo Pfoertner, Sep 16 2011

STATUS

approved

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Last modified August 11 08:50 EDT 2020. Contains 336422 sequences. (Running on oeis4.)