A317047 Numbers k such that both k and k + 1 are deficient.

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

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