

A225115


Triangular numbers of the form p^k  1, where p is a prime number and k >= 2.


1




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^21, the smallest being T(75055187665070250755513356704300447).  Giovanni Resta, Apr 29 2013


LINKS

Table of n, a(n) for n=1..9.


PROG

(PARI) t=0; for(n=1, 10^9, t+=n; if(isprimepower(t+1)>=2, print1(t, ", "))); \\ Joerg Arndt, Apr 29 2013


CROSSREFS

Cf. A006454, A025475.
Sequence in context: A068052 A068859 A006454 * A303353 A112228 A260511
Adjacent sequences: A225112 A225113 A225114 * A225116 A225117 A225118


KEYWORD

nonn,hard,more


AUTHOR

Alex Ratushnyak, Apr 29 2013


EXTENSIONS

a(9) from Giovanni Resta, Apr 29 2013


STATUS

approved



