OFFSET
1,11
COMMENTS
a(n+1) > a(n) iff n is in A009003. - Benoit Cloitre, Dec 08 2021
LINKS
Reiner Moewald and Robert Israel, Table of n, a(n) for n = 1..10000 (n = 1..500 from Reiner Moewald)
MAPLE
a046080:= proc(n) local F, t;
F:= select(t -> t[1] mod 4 = 1, ifactors(n)[2]);
1/2*(mul(2*t[2]+1, t=F)-1)
end proc:
ListTools:-PartialSums(map(a046080, [$0..100])); # Robert Israel, Jul 18 2016
MATHEMATICA
b[0] = b[1] = 0; b[n_] := With[{fi = Select[FactorInteger[n], Mod[#[[1]], 4] == 1&][[All, 2]]}, (Times @@ (2*fi + 1) - 1)/2];
Table[b[n], {n, 0, 100}] // Accumulate (* Jean-François Alcover, Feb 27 2019 *)
PROG
(PARI) a(n)=sum(a=1, n-3, sum(b=a+1, sqrtint((n-1)^2-a^2), issquare(a^2+b^2))) \\ Charles R Greathouse IV, Apr 29 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Reiner Moewald, Apr 19 2013
STATUS
approved