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 A164623 Primes p such that p*(p-1)/2-5 and p*(p-1)/2+5 are also prime numbers. 1
 13, 157, 673, 1069, 1117, 1153, 1213, 1597, 2029, 2089, 2437, 2713, 2833, 3613, 4057, 4909, 5653, 6337, 6529, 7549, 7993, 8053, 9613, 10789, 11497, 11689, 12073, 12373, 13309, 13669, 13789, 14173, 15289, 15937, 16249, 18097, 18637, 19249, 19993 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes A000040(k) such that A008837(k)+-5 are also prime numbers. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE 13 is in the sequence because 13*6-5=73 and 13*6+5=83 are both prime. MATHEMATICA Select[Prime[Range[2300]], PrimeQ[# (# - 1)/2 - 5] && PrimeQ[# (# - 1)/2 + 5] &] PROG (PARI) forprime(p=2, 10^6, my(b=binomial(p, 2)); if(isprime(b-5)&isprime(b+5), print1(p, ", "))); /* Joerg Arndt, Apr 10 2013 */ CROSSREFS Cf. A008846, A020882, A068228, A068229, A082539, A086519, A107159, A158708, A139494, A164620, A164621, A164622, A023203. Sequence in context: A140020 A130868 A154414 * A072841 A244206 A159499 Adjacent sequences:  A164620 A164621 A164622 * A164624 A164625 A164626 KEYWORD nonn,easy AUTHOR Vladimir Joseph Stephan Orlovsky, Aug 17 2009 EXTENSIONS Edited by R. J. Mathar, Aug 20 2009 Mathematica code adapted to the definition by Bruno Berselli, Apr 10 2013 STATUS approved

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Last modified April 5 19:56 EDT 2020. Contains 333260 sequences. (Running on oeis4.)