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A047779 Abundant or perfect numbers n such that neither n-1 nor n+1 is a prime. +0
1
56, 120, 144, 160, 176, 186, 204, 208, 216, 220, 246, 260, 288, 300, 304, 320, 324, 340, 342, 364 (list; graph; listen)
OFFSET

1,1

LINKS

Source

EXAMPLE

a(1) = 56 because 55 and 57 are composite and the sum of the divisors of 56 is 64 which is >= 56 and no integer < 56 has this property.

CROSSREFS

A023196 is a superset.

Sequence in context: A063347 A054891 A118161 this_sequence A044243 A044624 A038849

Adjacent sequences: A047776 A047777 A047778 this_sequence A047780 A047781 A047782

KEYWORD

easy,nonn

AUTHOR

Tony Davie (ad(AT)dcs.st-and.ac.uk)

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.


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