A204823 Sum of divisors (A000203) of deficient numbers (A005100).

1, 3, 4, 7, 6, 8, 15, 13, 18, 12, 14, 24, 24, 31, 18, 20, 32, 36, 24, 31, 42, 40, 30, 32, 63, 48, 54, 48, 38, 60, 56, 42, 44, 84, 78, 72, 48, 57, 93, 72, 98, 54, 72, 80, 90, 60, 62, 96, 104, 127, 84, 68, 126, 96, 72, 74, 114, 124, 140, 96, 80, 121, 126, 84, 108, 132

Offset

1,2

Comments

a(n) = A000203(A005100(n)) = A005100(n) + A205099(n).

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Deficient Number

Formula

a(n) < 8n/3. - Charles R Greathouse IV, Feb 19 2013

Mathematica

sddn[n_]:=Module[{s=DivisorSigma[1, n]}, If[s<2n, s, 0]]; DeleteCases[ sddn/@ Range[ 100], 0] (* Harvey P. Dale, Jan 02 2015 *)

Prog

(PARI) for(n=1, 300, s=sigma(n); if(s<2*n, print1(s", "))) \\ Charles R Greathouse IV, Feb 19 2013

Crossrefs

Cf. A204822 (sum of divisors of abundant numbers), A205099 (sum of proper divisors of deficient numbers).

Sequence in context: A132009 A295565 A086455 * A211657 A215430 A096842

Adjacent sequences: A204820 A204821 A204822 * A204824 A204825 A204826

Keyword

nonn

Author

Jaroslav Krizek, Jan 22 2012

Status

approved