A051333 - OEIS

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A051333

Euclid-Mullin sequence (A000945) with initial value a(1)=257 instead of a(1)=2.

257, 2, 5, 3, 11, 84811, 31, 7, 1560842137471, 20113, 17, 83, 47, 339491, 7814561, 109, 2897, 16103, 70921439, 199, 1381, 34987489236924545883729121, 43, 241, 37, 491, 28468486915378661, 8803, 29, 25212511, 2311, 67, 3929, 1151, 192697, 797, 157, 23, 1489, 13

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

OFFSET

1,1

LINKS

Tyler Busby, Table of n, a(n) for n = 1..44

MATHEMATICA

a[1]=257; a[n_] := First[ Flatten[ FactorInteger[ 1+Product[ a[ j ], {j, 1, n-1} ] ] ] ]; Array[a, 10]

PROG

(PARI) spf(n)=my(f=factor(n)[1, 1]); f \\ A020639

first(m)=my(v=vector(m)); v[1]=257; for(i=2, m, v[i]=spf(1+prod(j=1, i-1, v[j]))); v \\ Anders Hellström, Dec 07 2015

CROSSREFS

Cf. A020639, A000945, A000946, A005265, A005266.