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A176774 Smallest polygonality of n = smallest integer m>=3 such that n is m-gonal number. 8
3, 4, 5, 3, 7, 8, 4, 3, 11, 5, 13, 14, 3, 4, 17, 7, 19, 20, 3, 5, 23, 9, 4, 26, 10, 3, 29, 11, 31, 32, 12, 7, 5, 3, 37, 38, 14, 8, 41, 15, 43, 44, 3, 9, 47, 17, 4, 50, 5, 10, 53, 19, 3, 56, 20, 11, 59, 21, 61, 62, 22, 4, 8, 3, 67, 68, 24, 5, 71, 25, 73, 74, 9, 14, 77, 3, 79, 80, 4, 15, 83 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

A176775(n) gives the index of n as a(n)-gonal number.

Since n is the second n-gonal number, a(n) <= n. Furthermore, a(n)=n iff A176775(n)=2.

LINKS

Table of n, a(n) for n=3..83.

Weisstein, Eric W. Polygonal Number. MathWorld.

CROSSREFS

Cf. A090466, A090467.

Sequence in context: A123901 A214682 A093395 * A126352 A094758 A100394

Adjacent sequences:  A176771 A176772 A176773 * A176775 A176776 A176777

KEYWORD

nonn

AUTHOR

Max Alekseyev, Apr 25 2010

STATUS

approved

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Last modified May 22 03:34 EDT 2013. Contains 225511 sequences.