

A085779


Smallest m such that the triangular number A000217(n) divides m!.


2



1, 3, 3, 5, 5, 7, 7, 6, 6, 11, 11, 13, 13, 7, 5, 17, 17, 19, 19, 7, 11, 23, 23, 10, 13, 13, 9, 29, 29, 31, 31, 11, 17, 17, 7, 37, 37, 19, 13, 41, 41, 43, 43, 11, 23, 47, 47, 14, 14, 17, 17, 53, 53, 11, 11, 19, 29, 59, 59, 61, 61, 31, 8, 13, 13, 67, 67, 23, 23, 71, 71, 73, 73, 37, 19, 19
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..76.


FORMULA

a(n) = A002034(A000217(n)).


EXAMPLE

t(4)=10 and the first factorial divisible by 10 is 5!, so a(4)=5


MATHEMATICA

nn=80; With[{f=Range[nn]!, trs=Accumulate[Range[nn]]}, Flatten[ Table[ Position[f, _?(Divisible[#, trs[[n]]]&), {1}, 1], {n, nn}]]] (* Harvey P. Dale, Nov 18 2013 *)


PROG

(PARI) t(n)=n*(n+1)/2 for (n=1, 50, c=1; while (c!%t(n)!=0, c++); print1(c", "))


CROSSREFS

Sequence in context: A233808 A141424 A069902 * A078936 A293702 A061794
Adjacent sequences: A085776 A085777 A085778 * A085780 A085781 A085782


KEYWORD

nonn


AUTHOR

Jon Perry, Jul 23 2003


EXTENSIONS

Extended by Ray Chandler, Jun 06 2008


STATUS

approved



