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 A103153 a(n) is the 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 Hugo Pfoertner, Table of n, a(n) for n = 1..10000 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 5 17:42 EDT 2024. Contains 374953 sequences. (Running on oeis4.)