A155572 Intersection of A000404, A154777 and A154778: N = a^2 + b^2 = c^2 + 2d^2 = e^2 + 5f^2 for some positive integers a,b,c,d,e,f.

41, 89, 164, 225, 241, 281, 356, 369, 401, 409, 449, 521, 569, 601, 641, 656, 761, 769, 801, 809, 881, 900, 929, 964, 1009, 1025, 1049, 1124, 1129, 1201, 1249, 1289, 1321, 1361, 1409, 1424, 1476, 1481, 1489, 1521, 1601, 1604, 1609, 1636, 1681, 1721, 1796

Offset

1,1

Links

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

Prog

(PARI) isA155572(n, /* optional 2nd arg allows us to get other sequences */c=[5, 2, 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, isA155572(n) & print1(n", "))

Crossrefs

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

Sequence in context: A188173 A142411 A139924 * A356246 A107145 A087857

Adjacent sequences: A155569 A155570 A155571 * A155573 A155574 A155575

Keyword

easy,nonn

Author

M. F. Hasler, Jan 25 2009

Status

approved