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A321533
Numbers k such that sigma(k) = sigma(k+19), where sigma(k) is the sum of the divisors of k.
0
34, 158, 226, 266, 459, 3045, 3518, 3914, 4305, 6236, 8307, 10538, 10574, 18183, 23228, 25346, 25916, 33866, 33998, 48614, 49119, 51015, 56506, 63986, 72267, 82916, 94695, 100634, 144507, 154203, 186879, 269307, 281979, 308926, 358298, 358587, 367802, 380727, 382755, 412796, 474183
OFFSET
1,1
REFERENCES
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 34, pp 13, Ellipses, Paris 2008.
EXAMPLE
sigma(34) = sigma(34+19) = 54.
MATHEMATICA
Select[Range[10^6], DivisorSigma[1, #] == DivisorSigma[1, # + 19] &] (* Vincenzo Librandi, Nov 13 2018 *)
PROG
(PARI) isok(n) = sigma(n+19) == sigma(n); \\ Michel Marcus, Nov 13 2018
(Magma) [n: n in [1..2*10^6] | SumOfDivisors(n) eq SumOfDivisors(n + 19)]; // Vincenzo Librandi, Nov 13 2018
CROSSREFS
Cf. A000203.
Sequence in context: A167241 A028470 A221806 * A345157 A345126 A212407
KEYWORD
nonn
AUTHOR
Jud McCranie, Nov 12 2018
STATUS
approved