A155566 Intersection of A001481 and A002481: N = a^2 + b^2 = c^2 + 6d^2 for some integers a,b,c,d.

0, 1, 4, 9, 10, 16, 25, 36, 40, 49, 58, 64, 73, 81, 90, 97, 100, 106, 121, 144, 145, 160, 169, 193, 196, 202, 225, 232, 241, 250, 256, 265, 289, 292, 298, 313, 324, 337, 346, 360, 361, 388, 394, 400, 409, 424, 433, 441, 457, 484, 490, 505, 522, 529, 538, 576

Offset: 1

Author

M. F. Hasler, Jan 25 2009

Keywords

• easy
• nonn

Comments

Contains A155576 as a subsequence (obtained by restricting a,b,c,d to be nonzero). Also contains A000290 (squares) as subsequence.

Crossrefs

Cf. A001481, A002479, A003136, A002481, A020668 ff.

Programs

PARI

isA155566(n,/* use optional 2nd arg to get other analogous sequences */c=[6,1]) = { for(i=1,#c, for(b=0,sqrtint(n\c[i]), issquare(n-c[i]*b^2) & next(2)); return);1}
for( n=1,600, isA155566(n) & print1(n","))