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A181816 a(n) is the smallest integer that, upon multiplying any divisor of A025487(n), produces a member of A025487. 4
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 (list; graph; refs; listen; history; text; internal format)
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: A083273 A193163 A106157 * A113738 A287854 A245714

Adjacent sequences:  A181813 A181814 A181815 * A181817 A181818 A181819

KEYWORD

nonn

AUTHOR

Matthew Vandermast, Nov 30 2010

STATUS

approved

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Last modified November 30 20:17 EST 2021. Contains 349425 sequences. (Running on oeis4.)