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A071559 Smallest k such that n + k and n^2 + k^2 are simultaneously primes. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 22 06:12 EST 2019. Contains 320389 sequences. (Running on oeis4.)