A076721 - OEIS

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A076721

Difference between product of divisors of n and sum of divisors of n.

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

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OFFSET

1,6

COMMENTS

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

LINKS

Metin Sariyar, Table of n, a(n) for n = 1..5000

MATHEMATICA

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

CROSSREFS

Equals A007955 - A000203.

Sequence in context: A103903 A280631 A040599 * A232988 A292781 A090215

Adjacent sequences: A076718 A076719 A076720 * A076722 A076723 A076724

KEYWORD

sign

AUTHOR

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

EXTENSIONS

Edited by Robert G. Wilson v, Oct 29 2002

STATUS

approved