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A015883
Numbers k such that sigma(k) = sigma(k+13).
15
182, 782, 1965, 2486, 2678, 2685, 12141, 12441, 17342, 21242, 27686, 34905, 35505, 35853, 38662, 38985, 56732, 63578, 104342, 109461, 192933, 198909, 222122, 236966, 245349, 251654, 256322, 261885, 262238, 324441, 333909
OFFSET
1,1
REFERENCES
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 182, p. 56, Ellipses, Paris 2008.
LINKS
MATHEMATICA
Select[Range[350000], DivisorSigma[1, #]==DivisorSigma[1, # + 13] &] (* Vincenzo Librandi, Mar 10 2014 *)
PROG
(PARI) is(n)=sigma(n)==sigma(n+13) \\ Charles R Greathouse IV, Mar 09 2014
KEYWORD
nonn
EXTENSIONS
Corrected by T. D. Noe, Oct 31 2006
STATUS
approved