A396644 - OEIS

%I #18 Jul 08 2026 21:26:00

%S 0,0,1,2,4,6,11,16,27,42,65,109,173,304,501,860,1518,2678,4749,8500,

%T 15320,27765,50326,91996,168285,309294,571477,1057147,1962048,3650516,

%U 6810112,12740284,23875506,44842400,84384850,159089621,300415965,568225074,1076428659

%N Number of cousin primes < 2^n.

%C Only the upper prime of each pair is counted, e.g. the pair (7,11) is counted in a(4), not a(3).

%H Benjamin Chaffin, <a href="/A396644/b396644.txt">Table of n, a(n) for n = 1..63</a>

%Y Cf. A080840, A007053, A033843, A341843.

%K nonn,changed

%O 1,4

%A _Benjamin Chaffin_, Jun 01 2026