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A225115
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Triangular numbers of the form p^k - 1, where p is a prime number and k >= 2.
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1
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OFFSET
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1,1
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COMMENTS
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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
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LINKS
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PROG
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(PARI) t=0; for(n=1, 10^9, t+=n; if(isprimepower(t+1)>=2, print1(t, ", "))); \\ Joerg Arndt, Apr 29 2013
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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