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

1,3

Comments

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

Links

Table of n, a(n) for n=1..56.

Prog

(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", "))

Crossrefs

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

Sequence in context: A117570 A337816 A272266 * A305231 A312832 A236652

Adjacent sequences: A155563 A155564 A155565 * A155567 A155568 A155569

Keyword

easy,nonn

Author

M. F. Hasler, Jan 25 2009

Status

approved