A217583 Numbers n^2+1 such that (n-1)^2+1 and (n+1)^2+1 are prime.

10, 26, 226, 626, 3026, 15626, 42026, 148226, 216226, 403226, 416026, 511226, 1199026, 1311026, 1380626, 1550026, 1625626, 1729226, 1890626, 2449226, 2608226, 2805626, 2839226, 3861226, 4223026, 4347226, 4389026, 5784026, 6027026, 6426226, 7102226, 8037226

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Maple

with(numtheory):for n from 1 to 500 do: x1:=n^2+1:x2:=(n+2)^2 + 1:if type(x1, prime)=true and type(x2, prime)=true then printf(`%d, `, (n+1)^2+1):else fi:od:

Mathematica

Select[Partition[Range[3000]^2+1, 3, 1], AllTrue[{#[[1]], #[[3]]}, PrimeQ]&][[All, 2]] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jan 03 2019 *)

Prog

(PARI) forstep(n=3, 1e3, 2, if(isprime(n^2+2*n+2) && isprime(n^2-2*n+2), print1(n^2+1", "))) \\ Charles R Greathouse IV, Oct 09 2012

Crossrefs

Cf. A002496, A108814.

Sequence in context: A259979 A368503 A235053 * A301606 A281510 A024168

Adjacent sequences: A217580 A217581 A217582 * A217584 A217585 A217586

Keyword

nonn

Author

Michel Lagneau, Oct 07 2012

Status

approved