OFFSET
1,1
COMMENTS
A037074 is a subsequence. - R. J. Mathar, Jun 08 2008
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..5400
MAPLE
with(numtheory): a:=proc(n) if type(sqrt(n+1), integer)=true and tau(n)=4 then n else end if end proc: seq(a(n), n=1..800000); # Emeric Deutsch, Jan 27 2008
MATHEMATICA
t={}; Do[If[DivisorSigma[0, n]==4&&IntegerQ[Sqrt[n+1]], AppendTo[t, n]], {n, 10^6}]; t (* Jayanta Basu, Jun 03 2013 *)
Select[Range[1000]^2-1, DivisorSigma[0, #]==4&] (* Harvey P. Dale, Jul 28 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Teofilatto, Jan 11 2008
EXTENSIONS
Edited and extended by Emeric Deutsch, Jan 27 2008
Name reworded by Jon E. Schoenfield, Jan 15 2019
STATUS
approved