

A055515


(2^n 1)/product(2^p 1) where the product is over all distinct primes p that divide n.


0



1, 1, 1, 5, 1, 3, 1, 85, 73, 11, 1, 195, 1, 43, 151, 21845, 1, 12483, 1, 11275, 2359, 683, 1, 798915, 1082401, 2731, 19173961, 704555, 1, 1649373, 1, 1431655765, 599479, 43691, 8727391, 3272356035, 1, 174763, 9588151, 11822705675, 1, 1649061309, 1
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OFFSET

1,4


LINKS

Table of n, a(n) for n=1..43.


FORMULA

For p prime, a(p) = 1.  Michel Marcus, May 18 2014
For p prime, a(p^2) = A051156(n).  Michel Marcus, May 18 2014


EXAMPLE

a(12) = (2^12 1)/((2^2 1) (2^3 1)) = 195.


PROG

(PARI) a(n) = my(f = factor(n)); (2^n1)/prod(i=1, #f~, 2^f[i, 1] 1); \\ Michel Marcus, May 18 2014


CROSSREFS

Sequence in context: A155059 A206076 A115638 * A215010 A136744 A068237
Adjacent sequences: A055512 A055513 A055514 * A055516 A055517 A055518


KEYWORD

easy,nonn


AUTHOR

Leroy Quet, Jul 03 2000


STATUS

approved



