A309055 Record values of A309036.

2, 17, 20, 43, 107, 142, 176, 1291, 1748, 3309, 5114, 9412, 13032, 53799, 62195, 258834, 515752, 590919, 1880056, 4387977, 4982469, 8725487, 10021836, 22701799, 34769113, 75672055, 3847032954, 6476460401, 8607624876, 13054048917, 40404144055, 55300901872

Offset: 1

Author

Robert Israel, Jul 09 2019

Keywords

• nonn

Examples

			a(3) = 20 is a term because A309036(25) = 20 and A309036(k) < 20 for k < 25.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..37

Crossrefs

Cf. A309036, A309056.

Programs

Maple

S1:= 0: S2:= 0: Recv:= NULL: count:= 0:
maxv:= 0:
for n from 1 to 200000 do
  p:= ithprime(n);
  S1:= S1 + p;
  S2:= S2 + n*p;
  v:= igcd(S1, S2);
  if v > maxv then
    maxv:= v;
    count:= count+1;
    Recv:= Recv,v;
  fi
od:
Recv;

PARI

lista(nn) = {my(k=r=s=t=0); forprime(p=2, nn, if(gcd(s+=p, t+=(k++)*p)>r, r=gcd(s,t); print1(r, ", "))); } \\ Jinyuan Wang, Apr 16 2020

Formula

a(n) = A309036(A309056(n)).

Extensions

a(16)-a(27) from Rémy Sigrist, Jul 09 2019

a(28) from Jinyuan Wang, Apr 16 2020

Terms a(29) and beyond from Giovanni Resta, Apr 19 2020