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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
OFFSET
1,2
LINKS
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
KEYWORD
nonn
AUTHOR
Muniru A Asiru, Aug 04 2018
STATUS
approved