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A317047 Numbers k such that both k and k + 1 are deficient. 6
1, 2, 3, 4, 7, 8, 9, 10, 13, 14, 15, 16, 21, 22, 25, 26, 31, 32, 33, 34, 37, 38, 43, 44, 45, 46, 49, 50, 51, 52, 57, 58, 61, 62, 63, 64, 67, 68, 73, 74, 75, 76, 81, 82, 85, 86, 91, 92, 93, 94, 97, 98, 105, 106, 109, 110, 115, 116, 117, 118, 121, 122, 123 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Muniru A Asiru, Table of n, a(n) for n = 1..10000

MAPLE

A:=select(k->sigma(k)<2*k, [$1..200]): a:=seq(A[i], i in select(n->A[n+1]-A[n]=1, [$1..nops(A)-1]));

PROG

(GAP) A:=Filtered([1..200], k->Sigma(k)<2*k);;

a:=List(Filtered([1..Length(A)-1], i->A[i+1]-A[i]=1), j->A[j]);

(PARI) isok(n) = (sigma(n) < 2*n) && (sigma(n+1) < 2*(n+1)); \\ Michel Marcus, Aug 20 2018

CROSSREFS

Subsequence of A005100.

Numbers j such that both k and k + j are consecutive deficient numbers: this sequence (j=1), A317048 (j=2), A317049 (j=3).

Sequence in context: A332485 A031477 A047227 * A228102 A261412 A112965

Adjacent sequences:  A317044 A317045 A317046 * A317048 A317049 A317050

KEYWORD

nonn

AUTHOR

Muniru A Asiru, Aug 04 2018

STATUS

approved

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Last modified May 26 00:08 EDT 2020. Contains 334613 sequences. (Running on oeis4.)