OFFSET
1,3
LINKS
Paolo P. Lava, Table of n, a(n) for n = 1..1000
EXAMPLE
0 = 0^2; 1 = 1^2; 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36 = 6^2.
MAPLE
with(numtheory): P:=proc(q) local a, b, c, k, n; a:=0; for n from 0 to q do b:=0; c:=n;
for k from 1 to ilog10(n)+1 do b:=b+(c mod 10); c:=trunc(c/10); od; a:=a+b;
if a=trunc(sqrt(a))*trunc(sqrt(a)) then print(a); fi; od; end: P(10^6);
MATHEMATICA
Select[Accumulate@ Map[Total@ IntegerDigits@ # &, Range[0, 10^4]], IntegerQ@ Sqrt@ # &] (* Michael De Vlieger, Apr 11 2016 *)
PROG
(PARI) lista(nn) = for (n=0, nn, if (issquare(s=sum(k=1, n, sumdigits(k))), print1(s, ", "))); \\ Michel Marcus, Apr 11 2016
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
Paolo P. Lava, Apr 11 2016
STATUS
approved