A071559 Smallest k such that n + k and n^2 + k^2 are simultaneously primes.

1, 1, 2, 1, 2, 1, 10, 3, 4, 1, 6, 7, 10, 9, 2, 1, 2, 5, 10, 3, 10, 15, 8, 5, 4, 5, 2, 13, 30, 11, 6, 5, 8, 9, 2, 1, 30, 3, 34, 1, 20, 5, 10, 9, 2, 15, 20, 13, 4, 11, 16, 7, 20, 25, 4, 11, 2, 3, 14, 13, 10, 17, 38, 9, 2, 1, 22, 5, 10, 3, 26, 7, 28, 5, 4, 21, 12

Offset

1,3

Links

Bill McEachen, Table of n, a(n) for n = 1..1000

Mathematica

Table[SelectFirst[Range[120], AllTrue[{n + #, n^2 + #^2}, PrimeQ] &], {n, 77}] (* Michael De Vlieger, Feb 22 2018 *)

Prog

(PARI) for(n=1, 100, s=1; while(isprime(s^2+n^2)*isprime(s+n)==0, s++); print1(s, ", "))

Crossrefs

Sequence in context: A124781 A124151 A110179 * A071560 A248516 A097749

Adjacent sequences: A071556 A071557 A071558 * A071560 A071561 A071562

Keyword

easy,nonn

Author

Benoit Cloitre, May 30 2002

Status

approved