A051313 Euclid-Mullin sequence (A000945) with initial value a(1)=23 instead of a(1)=2.

23, 2, 47, 3, 13, 84319, 7109609443, 463, 23403050994721829453179, 7, 5, 57367, 239, 40237, 10575444619218059847586376042094152838881224222904607376771, 31333, 742759, 9444637217

Offset: 1

Author

Labos Elemer

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..37

Crossrefs

Cf. A000945, A000946, A005265, A005266.

Programs

Mathematica

a[1]=23; a[n_] := First[ Flatten[ FactorInteger[ 1+Product[ a[ j ], {j, 1, n-1} ] ] ] ]; Array[a, 10]

PARI

spf(n)=factor(n)[1, 1]
first(m)=my(v=vector(m)); v[1]=23; for(i=2, m, v[i]=spf(1+prod(j=1, i-1, v[j]))); v; \\ Anders Hellström, Nov 22 2015

Extensions

a(18)-a(37) from Robert Price, Jul 17 2015