OFFSET
1,2
COMMENTS
a(12) > 10^15. - Jon E. Schoenfield, Oct 11 2015
a(14) > 3*10^21. The first 13 terms are the sums of the first 1, 21, 141, 331, 354, 4555, 5785, 6949, 8110, 104070, 360930, 551460217, 3061889301 squarefree numbers. - Giovanni Resta, Aug 19 2018
EXAMPLE
The sum of the first 14 squarefree integers is 1 + 2 + 3 + 5 + 6 + 7 + 10 + 11 + 13 + 14 + 15 + 17 + 19 + 21 = 144, a square.
PROG
(PARI) lista(nn) = {s = 0; i = 0; for (n=1, nn, if (issquarefree(n), i++; s += n; if (issquare(s), print1(s, ", ")); ); ); }
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Michel Marcus, Oct 01 2015
EXTENSIONS
a(12)-a(13) from Giovanni Resta, Aug 19 2018
STATUS
approved