OFFSET
1,2
COMMENTS
a(15) > 2*10^21. - Donovan Johnson, Feb 17 2010
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..20
PROG
(PARI) for(n=1, 3000, x=sum(k=1, n, sigma(k)); if(issquare(x), print1(x, ", "), ))
(PARI) { n=0; for (m=1, 10^5, x=sum(k=1, m, sigma(k)); if (issquare(x), write("b062407.txt", n++, " ", x); if (n==8, break)) ) } \\ Harry J. Smith, Aug 07 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 08 2001
EXTENSIONS
Terms a(7) and a(8) added by Harry J. Smith, Aug 07 2009
a(9)-a(14) from Donovan Johnson, Feb 17 2010
a(15)-a(17) from Giovanni Resta, Nov 22 2019
STATUS
approved