A155564 Intersection of A002479 and A003136: N = a^2 + 2b^2 = c^2 + 3d^2 for some integers a,b,c,d.

0, 1, 3, 4, 9, 12, 16, 19, 25, 27, 36, 43, 48, 49, 57, 64, 67, 73, 75, 76, 81, 97, 100, 108, 121, 129, 139, 144, 147, 163, 169, 171, 172, 192, 193, 196, 201, 211, 219, 225, 228, 241, 243, 256, 268, 283, 289, 291, 292, 300, 304, 307, 313, 324, 331, 337, 361, 363

Offset

1,3

Comments

Contains A155574 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..58.

Prog

(PARI) isA155564(n, /* use optional 2nd arg to get other analogous sequences */c=[3, 2]) = { for(i=1, #c, for(b=0, sqrtint(n\c[i]), issquare(n-c[i]*b^2) & next(2)); return); 1}
for( n=1, 500, isA155564(n) & print1(n", "))

Crossrefs

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

Sequence in context: A127163 A058503 A112169 * A105137 A243185 A336166

Adjacent sequences: A155561 A155562 A155563 * A155565 A155566 A155567

Keyword

easy,nonn

Author

M. F. Hasler, Jan 25 2009

Status

approved