A104359 - OEIS

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A104359

Greatest prime factor of A104357(n) = A104350(n) - 1.

1, 5, 11, 59, 179, 1259, 229, 7559, 37799, 415799, 17569, 71437, 18979, 62597, 1135133999, 1646947, 445771, 277021, 5499724229999, 2217247573, 721381, 46313123, 29220034833989999, 16347569521, 5464930609, 4939567, 319699160368361, 2605998587146349, 178974179, 15701603, 116318025830291273, 126202964557

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,2

LINKS

Tyler Busby, Table of n, a(n) for n = 2..159 (terms 2..74 from Amiram Eldar, terms 75..145 from Max Alekseyev)

Reinhard Zumkeller, Products of largest prime factors of numbers <= n

FORMULA

a(n) = A006530(A104357(n)).

MATHEMATICA

a[n_] := FactorInteger[-1 + Product[FactorInteger[k][[-1, 1]], {k, 1, n}]][[-1, 1]]; Array[a, 50, 2] (* Amiram Eldar, Feb 12 2020 *)

PROG

(PARI) gpf(n) = if (n==1, 1, vecmax(factor(n)[, 1])); \\ A006530