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A075753 Smallest prime factor of n-th odd triangular number. 0
3, 3, 3, 3, 5, 7, 3, 3, 3, 3, 11, 5, 3, 3, 3, 3, 5, 19, 3, 3, 3, 3, 23, 5, 3, 3, 3, 3, 29, 31, 3, 3, 3, 3, 5, 37, 3, 3, 3, 3, 41, 5, 3, 3, 3, 3, 5, 7, 3, 3, 3, 3, 53, 5, 3, 3, 3, 3, 7, 11, 3, 3, 3, 3, 5, 7, 3, 3, 3, 3, 11, 5, 3, 3, 3, 3, 5, 79, 3, 3, 3, 3, 83, 5, 3, 3, 3, 3, 89, 7, 3, 3, 3, 3, 5, 97, 3, 3, 3 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

As A014493(n)=binomial(A042963(n),2) and a(n)=A020639(A014493(n))>2, A014493(n) is a good binomial coefficient.

LINKS

Eric Weisstein's World of Mathematics, Triangular Number.

Eric Weisstein's World of Mathematics, Good Binomial Coefficient.

Eric Weisstein's World of Mathematics, Least Prime Factor.

CROSSREFS

Cf. A069901.

Sequence in context: A129756 A156724 A196186 * A006166 A142716 A195758

Adjacent sequences:  A075750 A075751 A075752 * A075754 A075755 A075756

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 11 2003

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Last modified February 17 16:49 EST 2012. Contains 206058 sequences.