A055257 Sums of two powers of 6.

2, 7, 12, 37, 42, 72, 217, 222, 252, 432, 1297, 1302, 1332, 1512, 2592, 7777, 7782, 7812, 7992, 9072, 15552, 46657, 46662, 46692, 46872, 47952, 54432, 93312, 279937, 279942, 279972, 280152, 281232, 287712, 326592, 559872, 1679617, 1679622, 1679652, 1679832

Offset

0,1

Links

T. D. Noe, Rows n = 0..100 of triangle, flattened

Formula

a(n) = 6^(n-trinv(n))+6^trinv(n), where trinv(n) = floor((1+sqrt(1+8*n))/2) = A002262(n) and n-trinv(n) = A003056(n)

Regarded as a triangle T(n, k) = 6^n + 6^k, so as a sequence a(n) = 6^A002262(n) + 6^A003056(n).

Mathematica

t = 6^Range[0, 9]; Select[Union[Flatten[Table[i + j, {i, t}, {j, t}]]], # <= t[[-1]] + 1 &] (* T. D. Noe, Oct 09 2011 *)

Crossrefs

Cf. A052216.

Sequence in context: A073710 A326026 A092831 * A238366 A084068 A192772

Adjacent sequences: A055254 A055255 A055256 * A055258 A055259 A055260

Keyword

easy,nonn,tabl

Author

Henry Bottomley, Jun 22 2000

Status

approved