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A317045
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Numbers k such that A(k+1) = A(k) + 2, where A() = A005100() are the deficient numbers.
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2
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5, 10, 15, 16, 19, 22, 23, 28, 31, 32, 37, 42, 43, 46, 51, 54, 55, 60, 61, 64, 67, 68, 73, 76, 77, 78, 81, 84, 85, 90, 95, 100, 105, 106, 109, 114, 119, 122, 123, 128, 133, 134, 137, 142, 147, 150, 151, 152, 155, 158, 159, 164, 167, 168, 169, 172, 177, 182
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OFFSET
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1,1
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LINKS
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FORMULA
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Sequence is { k | A125238(k) = 2 }.
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MAPLE
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with(numtheory): A:=select(k->sigma(k)<2*k, [$1..300]):
a:=select(j->A[j+1]=A[j]+2, [$1..nops(A)-1]);
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MATHEMATICA
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Position[Differences[Select[Range[250], DivisorSigma[1, #] < 2*# &]], 2] // Flatten (* Amiram Eldar, Mar 15 2024 *)
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PROG
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(GAP) A:=Filtered([1..300], k->Sigma(k)<2*k);; a:=Filtered([1..Length(A)-1], i->A[i+1]=A[i]+2);
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CROSSREFS
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A317048 is the main sequence for this entry.
Numbers k such that A(k+1) = A(k) + j, where A() = A005100() are the deficient numbers: A317044 (j=1), this sequence (j=2), A317046 (k=3).
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KEYWORD
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nonn,changed
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AUTHOR
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STATUS
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approved
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