OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..100
EXAMPLE
61 is in the list since sigma(61)+d(61)=64 and sigma(62)+d(62)=100.
MATHEMATICA
Sqd[n_] := Sqrt[DivisorSigma[1, n] + DivisorSigma[0, n]]; t = {}; Do[If[IntegerQ[Sqd[n]] && IntegerQ[Sqd[n + 1]], AppendTo[t, n]], {n, 20000000}]; t
SequencePosition[Table[If[IntegerQ[Sqrt[DivisorSigma[0, n]+DivisorSigma[1, n]]], 1, 0], {n, 189*10^5}], {1, 1}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 31 2020 *)
PROG
(PARI) is(n)=issquare(sigma(n)+numdiv(n))&&issquare(sigma(n+1)+ numdiv(n+1)) \\ Charles R Greathouse IV, Apr 09 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Jayanta Basu, Apr 09 2013
STATUS
approved