A309056 Where records of A309036 occur.

1, 4, 25, 26, 43, 77, 201, 336, 881, 2144, 22305, 24113, 44349, 48748, 153884, 400161, 793873, 1195455, 5066329, 6227954, 11394871, 16233979, 18368369, 63843903, 80998288, 117335658, 246252769, 6420049930, 23198011949, 30432298548, 62709861290, 117888644809

Offset

1,2

Comments

Numbers m such that A309036(m) > A309036(k) for all k < m.

Links

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

Formula

A309055(n) = A309036(a(n)).

Example

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

Maple

S1:= 0: S2:= 0: Recn:= 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;
    Recn:= Recn, n;
  fi
od:
Recn;

Prog

(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(k, ", "))); } \\ Jinyuan Wang, Apr 16 2020

Crossrefs

Cf. A309036, A309055.

Sequence in context: A238515 A043067 A289273 * A095970 A297963 A020221

Adjacent sequences: A309053 A309054 A309055 * A309057 A309058 A309059

Keyword

nonn

Author

Robert Israel, Jul 09 2019

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

Status

approved