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A015876 Numbers k such that sigma(k) = sigma(k+8). 15
15, 69, 87, 102, 132, 175, 230, 638, 689, 1127, 1349, 1392, 2006, 5170, 6680, 8366, 8390, 11652, 11918, 12128, 16748, 19511, 19829, 23318, 24597, 24734, 25122, 27162, 28676, 30730, 32864, 37391, 37436, 37901, 41082, 45925, 47487 (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

A015876:=proc(q) local n;

for n from 1 to q do if sigma(n+8)=sigma(n) then print(n); fi; od; end:

A015876(10^10); # Paolo P. Lava, Mar 25 2013

MATHEMATICA

Select[Range[50000], DivisorSigma[1, #]==DivisorSigma[1, # + 8] &] (* Vincenzo Librandi, Mar 10 2014 *)

PROG

(PARI) is(n)=sigma(n)==sigma(n+8) \\ Charles R Greathouse IV, Mar 09 2014

CROSSREFS

Cf. A002961, A007373, A015861, A015863, A015865, A015866, A015867, A015877, A015880, A015881, A015882, A015883, A181647.

Sequence in context: A265141 A336624 A211917 * A201126 A085474 A212109

Adjacent sequences:  A015873 A015874 A015875 * A015877 A015878 A015879

KEYWORD

nonn

AUTHOR

Robert G. Wilson v

STATUS

approved

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Last modified July 5 04:50 EDT 2022. Contains 355087 sequences. (Running on oeis4.)