A317044 Numbers k such that A(k+1) = A(k) + 1, where A() = A005100() are the deficient numbers.
1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 14, 17, 18, 20, 21, 24, 25, 26, 27, 29, 30, 33, 34, 35, 36, 38, 39, 40, 41, 44, 45, 47, 48, 49, 50, 52, 53, 56, 57, 58, 59, 62, 63, 65, 66, 69, 70, 71, 72, 74, 75, 79, 80, 82, 83, 86, 87, 88, 89, 91, 92, 93, 94, 96, 97, 98
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Crossrefs
Programs
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GAP
A:=Filtered([1..150],k->Sigma(k)<2*k);; a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+1);
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Maple
with(numtheory): A:=select(k->sigma(k)<2*k,[$1..150]): a:=select(j->A[j+1]=A[j]+1,[$1..nops(A)-1]);
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Mathematica
Position[Differences[Select[Range[130], DivisorSigma[1, #] < 2*# &]], 1] // Flatten (* Amiram Eldar, Mar 15 2024 *)