OFFSET
1,1
COMMENTS
No terms == 1 (mod 4).
Numbers k such that A309036(k)=1. - Robert Israel, Jul 09 2019
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
N:= 1000: # for terms <= N
Primes:= map(ithprime, [$1..N]):
S1:= ListTools:-PartialSums(Primes):
S2:= ListTools:-PartialSums(zip(`*`, Primes, [$1..N])):
select(t -> igcd(S1[t], S2[t])=1, [$1..N]);
MATHEMATICA
okQ[n_] := With[{pp = Prime[Range[n]]}, CoprimeQ[Total[pp], Total[pp.Range[n]]]];
Select[Range[200], okQ] (* Jean-François Alcover, Dec 05 2023 *)
PROG
(PARI) isok(k) = my(vp=primes(k)); gcd(sum(i=1, k, vp[i]), sum(i=1, k, i*vp[i])) == 1; \\ Michel Marcus, Apr 07 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Apr 07 2019
STATUS
approved