A260725 a(1)=a(2)=a(3)=a(4)=a(5)=2; thereafter, a(n) = gpf(1 + Product_{k=1..5}(a(n-k)), where gpf is greatest prime factor.

2, 2, 2, 2, 2, 11, 59, 577, 13999, 232988779, 7616971, 141695022522269, 52247207549418855988531757, 784710183186946763762727466890094566789132493, 2696635801755076542772762485782137063037806561559423, 406892172682482048521833925827793697965504908008299460763

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..18

Anders Hellström, Sage program

Prog

(PARI) gpf(n)=my(v=factor(n)[, 1]); v[#v];
first(m)=my(v=[2, 2, 2, 2, 2], f=5); print1("2, 2, 2, 2, 2"); if(m>f, for(i=f+1, m, p=prod(j=1, f, v[i-j]) ; v=concat(v, gpf(p+1)); print1(" , ", v[i]); )); v

Crossrefs

Cf. A259828, A000945.

Sequence in context: A253633 A216844 A088050 * A058005 A095386 A060359

Adjacent sequences: A260722 A260723 A260724 * A260726 A260727 A260728

Keyword

nonn

Author

Anders Hellström, Jul 30 2015

Extensions

a(15) from Charles R Greathouse IV, Aug 06 2015

a(16) from Charles R Greathouse IV, Aug 10 2015

Status

approved