A155571 Intersection of A000404, A092572 and A154778: N = a^2 + b^2 = c^2 + 3d^2 = e^2 + 5f^2 for some positive integers a,b,c,d,e,f.

61, 109, 181, 229, 241, 244, 349, 409, 421, 436, 541, 549, 601, 661, 709, 724, 769, 829, 900, 916, 964, 976, 981, 1009, 1021, 1069, 1129, 1201, 1225, 1249, 1321, 1381, 1396, 1429, 1489, 1521, 1525, 1549, 1609, 1621, 1629, 1636, 1669, 1684, 1741, 1744, 1789

Offset

1,1

Links

Table of n, a(n) for n=1..47.

Prog

(PARI) isA155571(n, /* optional 2nd arg allows us to get other sequences */c=[5, 3, 1]) = { 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, 1999, isA155571(n) & print1(n", "))

Crossrefs

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

Sequence in context: A248431 A141919 A308797 * A107152 A141301 A139898

Adjacent sequences: A155568 A155569 A155570 * A155572 A155573 A155574

Keyword

easy,nonn

Author

M. F. Hasler, Jan 25 2009

Status

approved