A015881 Numbers k such that sigma(k) = sigma(k+11).

28, 154, 466, 874, 958, 1054, 2266, 2878, 11505, 12754, 14674, 17974, 21154, 21778, 29223, 29535, 31725, 32714, 39658, 43186, 48004, 52018, 62338, 70198, 126795, 132783, 163251, 164818, 207603, 212938, 221595, 272685, 274527

Offset

1,1

Links

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

Mathematica

Select[Range[300000], DivisorSigma[1, #]==DivisorSigma[1, # + 11] &] (* Vincenzo Librandi, Mar 10 2014 *)
Position[Partition[DivisorSigma[1, Range[300000]], 12, 1], _?(First[#]== Last[#]&), 1, Heads->False]//Flatten (* Harvey P. Dale, Aug 20 2017 *)

Prog

(PARI) is(n)=sigma(n)==sigma(n+11) \\ Charles R Greathouse IV, Mar 09 2014

Crossrefs

Cf. A002961, A007373, A015861, A015863, A015865, A015866, A015867, A015876, A015877, A015880, A015882, A015883, A181647.

Sequence in context: A271636 A188778 A002593 * A026910 A172220 A255151

Adjacent sequences: A015878 A015879 A015880 * A015882 A015883 A015884

Keyword

nonn

Author

Robert G. Wilson v

Status

approved