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A271322 Largest prime factor of the n-th n-gonal number (A060354). 4
2, 3, 2, 7, 11, 7, 11, 29, 37, 23, 7, 67, 79, 23, 53, 17, 137, 19, 43, 191, 211, 29, 127, 277, 43, 163, 11, 379, 37, 109, 233, 71, 23, 281, 149, 631, 29, 13, 53, 71, 821, 431, 113, 947, 991, 47, 541, 1129, 107, 613, 29, 1327, 197, 179, 743, 67, 1597, 827 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Colin Barker, Table of n, a(n) for n = 2..1000

FORMULA

a(n) = A006530(A060354(n)).

EXAMPLE

a(5) = 7 because A060354(5) = 35 = 5 * 7.

PROG

(PARI)

pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ n-th m-gonal number

lpf(m) = vecmax(factorint(m)[, 1]) \\ Largest prime factor

a(n) = lpf(pg(n, n))

vector(100, n, n++; a(n))

CROSSREFS

Cf. A006530, A060354, A271319, A271320, A271321.

Sequence in context: A208930 A122076 A209774 * A170842 A014784 A048601

Adjacent sequences:  A271319 A271320 A271321 * A271323 A271324 A271325

KEYWORD

nonn

AUTHOR

Colin Barker, Apr 04 2016

STATUS

approved

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Last modified September 17 09:04 EDT 2019. Contains 327128 sequences. (Running on oeis4.)