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A058854 a(n) = largest prime in the factorization of (n+1)-st Franel number (A000172). 0
2, 5, 7, 173, 563, 73, 41, 369581, 1409, 109, 449, 176459, 44221, 12148537, 148381, 11399977, 5779337237, 16111, 26013917, 57405011, 3019, 1973, 191141, 6730949, 998917, 6619, 3853, 5153, 138961158000728258971, 2593, 6511107455627473 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..30.

EXAMPLE

a(3)=173 because the 4th Franel number is 346 = 2^1 * 173^1, in which 173 is the largest prime.

MAPLE

with(combinat): with(numtheory): A000172 := n->sum(binomial(n, k)^3, k=0..n): for n from 1 to 50 do printf(`%d, `, ifactors(A000172(n))[2][nops(ifactors(A000172(n))[2])][1]) od:

MATHEMATICA

Do[ Print[ FactorInteger[ Sum[ Binomial[n, k]^3, {k, 0, n}]] [[ -1, 1]] ], {n, 1, 32} ]

CROSSREFS

Cf. A000172.

Sequence in context: A265815 A041961 A242169 * A006275 A042673 A214705

Adjacent sequences:  A058851 A058852 A058853 * A058855 A058856 A058857

KEYWORD

nonn

AUTHOR

Felix Goldberg (felixg(AT)tx.technion.ac.il), Jan 30 2001

EXTENSIONS

More terms from James A. Sellers, Feb 01 2001

STATUS

approved

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Last modified July 27 05:26 EDT 2021. Contains 346305 sequences. (Running on oeis4.)