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A204823
Sum of divisors (A000203) of deficient numbers (A005100).
5
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
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
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 22 2012
STATUS
approved