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A134339 a(n) = product of the positive "non-isolated divisors" of (2n). A divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n. 1
2, 2, 6, 2, 2, 24, 2, 2, 6, 40, 2, 24, 2, 2, 180, 2, 2, 24, 2, 40, 252, 2, 2, 24, 2, 2, 6, 112, 2, 720, 2, 2, 6, 2, 2, 1728, 2, 2, 6, 40, 2, 1008, 2, 2, 16200, 2, 2, 24, 2, 40, 6, 2, 2, 24, 220, 112, 6, 2, 2, 720, 2, 2, 252, 2, 2, 3168, 2, 2, 6, 40, 2, 1728, 2, 2, 180, 2, 2, 3744, 2, 40, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No odd integer has any non-isolated divisors.

LINKS

Table of n, a(n) for n=1..81.

FORMULA

a(n) = A007955(2n) / A134338(2n). - Chandler

EXAMPLE

The divisors of 2*10 = 20 are 1,2,4,5,10,20. Of these, 1,2,4,5 are the non-isolated divisors. So a(10) = 1*2*4*5 = 40.

CROSSREFS

Cf. A134338.

Sequence in context: A126889 A205030 A278250 * A162299 A281552 A205506

Adjacent sequences:  A134336 A134337 A134338 * A134340 A134341 A134342

KEYWORD

nonn

AUTHOR

Leroy Quet, Oct 21 2007

EXTENSIONS

Extended by Ray Chandler, Jun 24 2008

STATUS

approved

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Last modified February 20 08:44 EST 2019. Contains 320325 sequences. (Running on oeis4.)