A217841 Fermat pseudoprimes n to base 3 for which sqrt(8*n + 1) is an integer.

91, 703, 1891, 2701, 7381, 8911, 10585, 12403, 16471, 18721, 29161, 38503, 41041, 49141, 79003, 88831, 93961, 104653, 115921, 146611, 188191, 218791, 226801, 269011, 286903, 314821, 334153, 364231, 385003, 497503, 534061, 597871, 665281, 721801, 736291, 765703, 873181, 954271, 1056331, 1237951

Offset: 1

Author

Marius Coman, Oct 12 2012

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Fermat Pseudoprime

Crossrefs

Cf. A005935, A210461 (subsequence).

Programs

PARI

list(lim)=my(v=List(),n); lim\=1; forstep(k=27,sqrtint(8*lim+1),2, n=k^2>>3; if(Mod(3,n)^(n-1)==1, listput(v,n))); Vec(v) \\ Charles R Greathouse IV, Jun 30 2017

Extensions

a(15)-a(18) and a(35) from Charles R Greathouse IV, Jun 30 2017