A181816 a(n) is the smallest integer that, upon multiplying any divisor of A025487(n), produces a member of A025487.

1, 1, 1, 2, 1, 2, 1, 2, 12, 1, 4, 2, 12, 1, 4, 2, 12, 1, 4, 24, 2, 360, 8, 12, 1, 4, 24, 2, 360, 8, 12, 1, 4, 24, 2, 360, 8, 144, 12, 1, 48, 4, 720, 16, 24, 2, 360, 8, 144, 12, 1

Offset

1,4

Comments

All terms also belong to A181818. Each member of A181818 appears infinitely often. a(A025487(m)) = a(A025487(n)) iff A025487(m) and A025487(n) have the same odd part (cf. A000265).

Links

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

Formula

If A025487(n) = Product p(i)^e(i), then a(n) = Product A002110(i-1)^e(i); i.e., a(n) = A181811(A025487(n)).

a(n) = A181817(n)/A025487(n).

Example

For any divisor d of 6 (d = 1, 2, 3, 6), 2*d (2, 4, 6, 12) is always a member of A025487. 2 is the smallest number with this relationship to 6; therefore, since 6 = A025487(4), a(4) = 2.

Crossrefs

Cf. A000265, A025487, A181811, A181817, A181818.

Sequence in context: A353398 A193163 A106157 * A113738 A287854 A355341

Adjacent sequences: A181813 A181814 A181815 * A181817 A181818 A181819

Keyword

nonn

Author

Matthew Vandermast, Nov 30 2010

Status

approved