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 A015880 Numbers k such that sigma(k) = sigma(k+10). 15
 21, 174, 270, 517, 572, 913, 992, 1002, 1420, 1633, 1830, 2622, 2958, 4170, 4747, 5539, 7520, 7544, 7729, 10184, 10783, 14863, 16165, 16520, 19837, 20935, 21584, 23161, 26840, 28544, 29737, 31453, 34510, 35571, 35611, 35845, 39560 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Donovan Johnson, Table of n, a(n) for n = 1..1000 A. Weingartner, On the Solutions of sigma(n) = sigma(n+k), Journal of Integer Sequences, Vol. 14 (2011), #11.5.5. MAPLE A015880:=proc(q) local n; for n from 1 to q do if sigma(n+10)=sigma(n) then print(n); fi; od; end: A015880(10^10); # Paolo P. Lava, Mar 25 2013 MATHEMATICA Select[Range[40000], DivisorSigma[1, #]==DivisorSigma[1, # + 10] &] (* Vincenzo Librandi, Mar 10 2014 *) PROG (PARI) is(n)=sigma(n)==sigma(n+10) \\ Charles R Greathouse IV, Mar 09 2014 CROSSREFS Cf. A002961, A007373, A015861, A015863, A015865, A015866, A015867, A015876, A015877, A015881, A015882, A015883, A181647. Sequence in context: A185128 A007261 A119105 * A113163 A090021 A254681 Adjacent sequences:  A015877 A015878 A015879 * A015881 A015882 A015883 KEYWORD nonn AUTHOR STATUS approved

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Last modified July 29 07:28 EDT 2021. Contains 346340 sequences. (Running on oeis4.)