

A096565


Final digits of the smallest triangular number starting with n!.


2



0, 1, 6, 15, 90, 10, 3, 9003, 45300, 9570, 5840220, 533564010, 5384225220, 412190739351, 244816773411, 682660400311, 275258914747246, 710284752537711, 152042178127701610, 6144469158651504786, 8516189439015621936
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OFFSET

1,3


LINKS



EXAMPLE

a(7) = 3 because the smallest triangular number starting with 7!=5040 is 50403 and so the last digit is 3.


PROG

(PARI) { A096565(n) = my(k, t); k=1; while(1, t=sqrtint(n!*8*10^k)+1; if(t%2==0, t++); t=(t^21)/8; if( t\10^k == n!, return(t%10^k)); k++ ); } \\ Max Alekseyev, Apr 25 2009


CROSSREFS



KEYWORD

base,nonn


AUTHOR



EXTENSIONS



STATUS

approved



