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A015882 Numbers k such that sigma(k) = sigma(k+12). 15
35, 104, 285, 287, 310, 329, 340, 345, 406, 609, 660, 736, 767, 957, 1067, 1207, 1242, 1768, 1786, 1817, 1824, 2047, 2288, 2407, 2672, 2686, 2714, 3009, 4012, 4387, 4653, 4847, 6179, 7532, 8366, 8920, 10005, 10528, 11140, 11670, 11951 (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

A015882:=proc(q) local n;

for n from 1 to q do if sigma(n+12)=sigma(n) then print(n); fi; od; end:

A015882(10^10); # Paolo P. Lava, Mar 25 2013

MATHEMATICA

Select[Range[20000], DivisorSigma[1, #]==DivisorSigma[1, # + 12] &] (* Vincenzo Librandi, Mar 10 2014 *)

PROG

(PARI) is(n)=sigma(n)==sigma(n+12) \\ Charles R Greathouse IV, Mar 09 2014

CROSSREFS

Cf. A002961, A007373, A015861, A015863, A015865, A015866, A015867, A015876, A015877, A015880, A015881, A015883, A181647.

Sequence in context: A044603 A063795 A282851 * A347384 A010085 A033852

Adjacent sequences:  A015879 A015880 A015881 * A015883 A015884 A015885

KEYWORD

nonn

AUTHOR

Robert G. Wilson v

STATUS

approved

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Last modified July 5 05:10 EDT 2022. Contains 355087 sequences. (Running on oeis4.)