A084789 Increasing gaps between 3-smooth numbers (lower end).

1, 4, 9, 12, 18, 36, 81, 108, 162, 256, 288, 324, 512, 576, 648, 768, 864, 1024, 1152, 1296, 1536, 1728, 2304, 2592, 3072, 3456, 4608, 5184, 6912, 9216, 10368, 13824, 20736, 27648, 41472, 82944, 165888, 196608, 221184, 262144, 294912, 331776

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A084790(n) - A084788(n).

a(n) = A003586(A084791(n)).

Mathematica

s = {}; m = 13; Do[n = 3^k; While[n <= 3^m, AppendTo[s, n]; n*=2], {k, 0, m}]; s = Union[s]; d = Differences @ s; v = DeleteDuplicates @ FoldList[Max, d]; Map[s[[First@ Position[d, #]]] &, v] //Flatten (* Amiram Eldar, Jan 30 2020 *)

Crossrefs

Cf. A003586, A061987, A084788, A084790, A084791.

Sequence in context: A376340 A348918 A181023 * A157650 A312866 A312867

Adjacent sequences: A084786 A084787 A084788 * A084790 A084791 A084792

Keyword

nonn

Author

Reinhard Zumkeller, Jun 03 2003

Status

approved