cp's OEIS Frontend

A344581 Numbers k such that A034387(k) and A101203(k) are both prime.

%I A344581 #7 May 25 2021 01:38:15
%S A344581 4,7,8,15,44,311,503,507,744,843,851,955,1164,1256,1287,1307,1312,
%T A344581 2163,2171,2244,2247,2368,2412,3143,3160,3872,3875,3952,4584,5088,
%U A344581 5236,5355,5364,5380,6211,6303,6307,6587,7243,7244,7436,7439,7860,8220,8268,9167,9283,9515,9519,9632,9692,9915,9919
%N A344581 Numbers k such that A034387(k) and A101203(k) are both prime.
%C A344581 Numbers k such that the sums of primes <= k and of nonprimes <= k are both prime (not necessarily distinct).
%C A344581 All terms == 0 or 3 (mod 4).
%H A344581 Robert Israel, <a href="/A344581/b344581.txt">Table of n, a(n) for n = 1..10000</a>
%e A344581 a(3) = 8 is a term because A034387(8) = 2+3+5+7 = 17 and A101203(8) = 1+4+6+8 = 19 are prime.
%p A344581 sp:= proc(n) option remember; if isprime(n) then procname(n-1)+[0,n] else procname(n-1)+[n,0] fi end proc:
%p A344581 sp(1):= [1,0]:
%p A344581 filter:= proc(n) andmap(isprime, sp(n)) end proc:
%p A344581 select(filter, [$1..10000]);
%Y A344581 Cf. A034387, A101203.  Intersection of A228102 and A344580.
%K A344581 nonn
%O A344581 1,1
%A A344581 _J. M. Bergot_ and _Robert Israel_, May 24 2021