A155712 Intersection of A092572 and A155716: N = a^2 + 3b^2 = c^2 + 6d^2 for some positive integers a,b,c,d.

7, 28, 31, 49, 63, 73, 79, 97, 100, 103, 112, 124, 127, 151, 175, 193, 196, 199, 217, 223, 241, 252, 271, 279, 292, 313, 316, 337, 343, 367, 388, 400, 409, 412, 433, 439, 441, 448, 457, 463, 484, 487, 496, 508, 511, 553, 567, 577, 601, 604, 607, 631, 657, 673

Offset

1,1

Links

Table of n, a(n) for n=1..54.

Prog

(PARI) isA155712(n, /* optional 2nd arg allows us to get other sequences */c=[6, 3]) = { for(i=1, #c, for(b=1, sqrtint((n-1)\c[i]), issquare(n-c[i]*b^2) & next(2)); return); 1}
for( n=1, 999, isA155712(n) & print1(n", "))

Crossrefs

Cf. A000404, A154777, A092572, A097268, A154778, A155716, A155717, A155560-A155578.

Sequence in context: A200974 A184331 A267432 * A015817 A103253 A321777

Adjacent sequences: A155709 A155710 A155711 * A155713 A155714 A155715

Keyword

easy,nonn

Author

M. F. Hasler, Jan 25 2009

Status

approved