A258581 a(1) = 2; for n > 1 if n is even a(n) = gpf(1 + Product_{odd m,m

2, 3, 2, 5, 2, 3, 23, 37, 17, 149, 761, 50647, 4799, 411527, 18871308021859, 10312625105789, 17838863896549, 57892815889963361050999657943, 2252973546284243766517, 1849093263449444009859625443689931115519009693

Offset: 1

Author

Anders Hellström, Jul 15 2015

Keywords

• nonn

Links

• Anders Hellström, Sage program
• Anders Hellström, Mercury program

Crossrefs

Cf. A000946, A005266.

Programs

PARI

gpf(n)=my(v=factor(n)[, 1]); v[#v];
main(size)=my(v=vector(size), i, odd=2, even=1); v[1]=2; for(i=2, size, if(i%2==0, v[i]=gpf(odd+1); even*=v[i], v[i]=gpf(even+1); odd*=v[i])); v;