A309055 - OEIS

%I #16 Apr 20 2020 05:35:31

%S 2,17,20,43,107,142,176,1291,1748,3309,5114,9412,13032,53799,62195,

%T 258834,515752,590919,1880056,4387977,4982469,8725487,10021836,

%U 22701799,34769113,75672055,3847032954,6476460401,8607624876,13054048917,40404144055,55300901872

%N Record values of A309036.

%H Giovanni Resta, <a href="/A309055/b309055.txt">Table of n, a(n) for n = 1..37</a>

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

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

%p S1:= 0: S2:= 0: Recv:= NULL: count:= 0:

%p maxv:= 0:

%p for n from 1 to 200000 do

%p   p:= ithprime(n);

%p   S1:= S1 + p;

%p   S2:= S2 + n*p;

%p   v:= igcd(S1, S2);

%p   if v > maxv then

%p     maxv:= v;

%p     count:= count+1;

%p     Recv:= Recv,v;

%p   fi

%p od:

%p Recv;

%o (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

%Y Cf. A309036, A309056.

%K nonn

%O 1,1

%A _Robert Israel_, Jul 09 2019

%E a(16)-a(27) from _Rémy Sigrist_, Jul 09 2019

%E a(28) from _Jinyuan Wang_, Apr 16 2020

%E Terms a(29) and beyond from _Giovanni Resta_, Apr 19 2020