A051312 Euclid-Mullin sequence (A000945) with initial value a(1)=19 instead of a(1)=2.

19, 2, 3, 5, 571, 271, 457, 397, 1123, 23, 103, 42572757267735264511, 313, 17, 16013177, 7951, 1259, 41, 1531, 11, 83, 53, 67, 7, 21397, 13, 1619, 1274209367143, 433, 37, 491, 29, 658837, 135202080527, 163, 587, 31, 2797, 35286479

Offset: 1

Author

Labos Elemer

Keywords

• nonn

Links

• Tyler Busby, Table of n, a(n) for n = 1..50 (terms 1..42 from Robert Price)

Crossrefs

Cf. A000945, A000946, A005265, A005266.

Programs

Mathematica

a[1]=19; 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]=19; for(i=2, m, v[i]=spf(1+prod(j=1, i-1, v[j]))); v; \\ Anders Hellström, Aug 31 2015