A121658 Primes neither of the n^2+1 nor n^2+n+1 form.

11, 19, 23, 29, 41, 47, 53, 59, 61, 67, 71, 79, 83, 89, 97, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 163, 167, 173, 179, 181, 191, 193, 199, 223, 227, 229, 233, 239, 251, 263, 269, 271, 277, 281, 283, 293, 311, 313, 317, 331, 337, 347, 349

Offset

1,1

Comments

Previous name: Primes not equal to [k*(k or k+1 or k+2)] + 1 where k is a natural number.

Primes not of the form n^2 + 1 and n^2 + n + 1 and (n+1)^2. Correct version!!

Primes not contained in A200975 (numbers on the diagonals of Ulam's spiral). - Bob Selcoe, Oct 27 2014

Links

Harvey P. Dale, Table of n, a(n) for n = 1..10000

Mathematica

Select[Prime[Range[100]], NoneTrue[{Sqrt[#-1], (Sqrt[4#-3]-1)/2}, IntegerQ]&] (* The program uses the NoneTrue function from Mathematica version 10 *) (* Harvey P. Dale, Dec 23 2015 *)

Prog

(PARI) lista(nn) = {forprime(p=2, nn, if (!issquare(p-1) && !ispolygonal((p-1)/2, 3), print1(p, ", ")); ); } \\ Michel Marcus, Oct 28 2014

Crossrefs

Cf. A200975.

Sequence in context: A335478 A136435 A246428 * A320867 A165947 A129517

Adjacent sequences: A121655 A121656 A121657 * A121659 A121660 A121661

Keyword

easy,nonn

Author

Giovanni Teofilatto, Sep 10 2006, Sep 12 2006

Extensions

Edited by R. J. Mathar, Aug 02 2008

Data corrected by Bob Selcoe and Michel Marcus, Oct 28 2014

Status

approved