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A272978 Numbers not in the range of the sum of perfect divisors function. 0
1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers which do not appear in A185351 or A187794; that is, there is no integer N whose sum of perfect divisors is equal to a(n) for any n.

LINKS

Table of n, a(n) for n=1..77.

CROSSREFS

Cf. A000396, subsequence of A132999, A185351 (complement), A187794.

Sequence in context: A097010 A132999 A054027 * A080907 A127161 A129657

Adjacent sequences:  A272975 A272976 A272977 * A272979 A272980 A272981

KEYWORD

nonn

AUTHOR

Timothy L. Tiffin, Jul 13 2016

STATUS

approved

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Last modified July 29 04:31 EDT 2021. Contains 346340 sequences. (Running on oeis4.)