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Search: id:A076721
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A076721 Difference between product of divisors of n and sum of divisors of n. +0
1
0, -1, -1, 1, -1, 24, -1, 49, 14, 82, -1, 1700, -1, 172, 201, 993, -1, 5793, -1, 7958, 409, 448, -1, 331716, 94, 634, 689, 21896, -1, 809928, -1, 32705, 1041, 1102, 1177, 10077605, -1, 1384, 1465, 2559910, -1, 3111600, -1, 85100, 91047, 2044, -1, 254803844, 286, 124907 (list; graph; listen)
OFFSET

1,6

COMMENT

a(p)=-1 iff p is a prime.

MATHEMATICA

Table[d = Divisors[n]; Apply[Times, d] - Apply[Plus, d], {n, 1, 50}]

CROSSREFS

Equals A007955 - A000203.

Sequence in context: A097190 A103903 A040599 this_sequence A090215 A040570 A040569

Adjacent sequences: A076718 A076719 A076720 this_sequence A076722 A076723 A076724

KEYWORD

sign

AUTHOR

Emrehan Halici (emrehan(AT)halici.com.tr), Oct 27 2002

EXTENSIONS

Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 29 2002

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Last modified December 1 13:27 EST 2009. Contains 167806 sequences.


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