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A015880 Numbers n such that sigma(n) = sigma(n + 10). 14
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

REFERENCES

A. Weingartner, On the Solutions of sigma(n) = sigma(n+k), Journal of Integer Sequences, Vol. 14 (2011), #11.5.5.

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..1000

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

Robert G. Wilson v

STATUS

approved

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Last modified April 22 21:39 EDT 2018. Contains 302916 sequences. (Running on oeis4.)