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A225115
Triangular numbers of the form p^k - 1, where p is a prime number and k >= 2.
1
3, 15, 120, 528, 4095, 139128, 160554240, 812293020528, 379188080252621270252095320
OFFSET
1,1
COMMENTS
There are at least other 4 terms greater than a(9) that can be easily obtained by solving the Diophantine equation T(n) = p^2-1, the smallest being T(75055187665070250755513356704300447). - Giovanni Resta, Apr 29 2013
PROG
(PARI) t=0; for(n=1, 10^9, t+=n; if(isprimepower(t+1)>=2, print1(t, ", "))); \\ Joerg Arndt, Apr 29 2013
CROSSREFS
Sequence in context: A068052 A068859 A006454 * A303353 A112228 A260511
KEYWORD
nonn,hard,more
AUTHOR
Alex Ratushnyak, Apr 29 2013
EXTENSIONS
a(9) from Giovanni Resta, Apr 29 2013
STATUS
approved