A250004 Numbers representable as x^y + x*y, where x>1, y>1 are integers (without multiplicity).

8, 14, 15, 24, 35, 36, 42, 48, 63, 76, 80, 93, 99, 120, 140, 142, 143, 168, 195, 224, 234, 255, 258, 272, 288, 323, 360, 364, 399, 440, 483, 528, 530, 536, 575, 624, 645, 675, 728, 747, 756, 783, 840, 899, 960, 1023, 1030, 1044, 1088, 1155, 1224, 1295, 1320, 1364, 1368

Offset

1,1

Comments

The sequence of numbers representable as x^y + x*y in two or more ways begins: 24, 76, 272, 1044, 2208, 4120, 16412. Example: 2208 = 46^2 + 46*2 = 3^7 + 3*7.

The subsequence of squares begins: 36, 1764.

Links

Table of n, a(n) for n=1..55.

Example

a(2) = 14 = 2^3 + 2*3.
a(3) = 15 = 3^2 + 3*2.
a(22) = 255 = 15^2 + 15*2.

Prog

(PARI) isok(n) = {for (p=2, floor(log(n)/log(2)), for (k=2, sqrtnint(n, p), if (n == k^p + p*k, return (1)); ); ); return (0); } \\ Michel Marcus, Jan 16 2015

Crossrefs

Cf. A253775.

Cf. A024036 is a subsequence, except first 2 terms.

Sequence in context: A219303 A082772 A103338 * A114456 A230422 A050681

Adjacent sequences: A250001 A250002 A250003 * A250005 A250006 A250007

Keyword

nonn

Author

Alex Ratushnyak, Jan 14 2015

Status

approved