OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10135 (from the b-file at A002961; terms 1..4804 from T. D. Noe)
FORMULA
a(n) = sigma(A002961(n))
MATHEMATICA
Transpose[Select[{DivisorSigma[1, First[#]], DivisorSigma[1, Last[#]]}&/@ Partition[Range[280000], 2, 1], First[#]==Last[#]&]][[1]] (* Harvey P. Dale, May 07 2012 *)
DivisorSigma[1, #]&/@SequencePosition[DivisorSigma[1, Range[280000]], {x_, x_}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 21 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Asher Auel, Jan 11 2000
STATUS
approved