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A333914 a(n) is the least integer m >= 3 such that n is m-gonal pyramidal number. 0
3, 4, 5, 6, 7, 8, 3, 10, 11, 12, 4, 14, 15, 16, 5, 18, 3, 20, 6, 22, 23, 24, 7, 26, 27, 28, 4, 30, 31, 32, 9, 3, 35, 36, 10, 38, 5, 40, 11, 42, 43, 44, 12, 46, 47, 48, 6, 50, 51, 52, 14, 4, 3, 56, 15, 58, 7, 60, 16, 62, 63, 64, 17, 66, 67, 68, 8, 70, 71, 72, 19, 5, 75, 76, 20, 78, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Table of n, a(n) for n=4..80.

Eric Weisstein's World of Mathematics, Pyramidal Number

Index to sequences related to pyramidal numbers

EXAMPLE

a(18) = 5 since 18 is a pentagonal pyramidal number, but not a square pyramidal or tetrahedral number.

CROSSREFS

Cf. A080851, A176774, A261720.

Sequence in context: A088243 A154660 A004492 * A140255 A050270 A202307

Adjacent sequences:  A333911 A333912 A333913 * A333915 A333916 A333917

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Apr 09 2020

STATUS

approved

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Last modified April 16 18:53 EDT 2021. Contains 343050 sequences. (Running on oeis4.)