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 A252891 Numbers n such that sigma(n) is a partition number. 2
 1, 2, 4, 8, 20, 26, 28, 29, 39, 41, 129, 430, 526, 591, 655, 731, 1388, 1622, 2249, 3734, 6841, 18752, 18772, 21332, 35017, 37337, 53173, 105557, 113377, 124753, 419029, 614153, 824149, 829333, 2192923, 2369654, 2538915, 3059853, 3388115, 3479244, 3557183 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert G. Wilson v, Table of n, a(n) for n = 1..65 EXAMPLE 26 is in the sequence because the sum of divisors of 26 is 1 + 2 + 13 + 26 = 42 and 42 is a partition number because the number of partitions of 10 is equal to 42. MATHEMATICA (* To extend the search beyond 50400, be sure to increase the length of partNums accordingly *) partNums = PartionsP[Range[50]]; Select[Range[100], MemberQ[partNums, DivisorSigma[1, #]] &] (* Alonso del Arte, Dec 24 2014 *) CROSSREFS Cf. A000041, A000203. Sequence in context: A124154 A296606 A222562 * A102634 A026520 A282983 Adjacent sequences:  A252888 A252889 A252890 * A252892 A252893 A252894 KEYWORD nonn AUTHOR Omar E. Pol, Dec 24 2014 EXTENSIONS a(11)-a(16) from Alonso del Arte, Dec 24 2014 More terms from Michel Marcus, Dec 27 2014 STATUS approved

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Last modified June 19 19:11 EDT 2019. Contains 324222 sequences. (Running on oeis4.)