A188425 Position of 2^n in A051037 (5-smooth numbers).

1, 2, 4, 7, 12, 19, 27, 38, 52, 68, 87, 110, 137, 167, 201, 240, 284, 332, 386, 446, 511, 582, 660, 745, 836, 934, 1041, 1155, 1277, 1407, 1545, 1692, 1849, 2015, 2190, 2376, 2571, 2777, 2994, 3222, 3461, 3711, 3974, 4249, 4535, 4834, 5147, 5473, 5811, 6164, 6531, 6911, 7306, 7716, 8142, 8582, 9039, 9511, 9999, 10503, 11024, 11563, 12119, 12692, 13283, 13892, 14519

Offset: 0

Author

Zak Seidov, Mar 30 2011

Keywords

• nonn

Examples

			2^0 = 1 = A051037(1), hence a(0) = 1.
a(25) = 934 because 2^25 = 33554432 = A051037(934).
		

Links

• Zak Seidov, Table of n, a(n) for n = 0..200

Crossrefs

Cf. A051037, A188426, A188427 (positions of powers of 3 and 5 in A051037).

Formula

A051037(a(n)) = 2^n.

a(n) ~ c * n^3, where c = log(2)^2/(6*log(3)*log(5)) = 0.045287775775708... - Vaclav Kotesovec and Amiram Eldar, Sep 22 2024