A370607 - OEIS

%I #14 Feb 23 2024 21:39:43

%S 0,1,2,4,5,6,8,9,12,13,16,18,19,20,21,22,25,26,27,30,31,33,36,37,39,

%T 41,42,43,44,45,46,47,48,50,52,55,56,57,59,60,63,66,67,68,69,70,71,75,

%U 77,78,81,82,85,86,87,88,89,92,93,94,95,96,98,99,100,103,104

%N 2-valuations of terms of A370606.

%H Chai Wah Wu, <a href="/A370607/b370607.txt">Table of n, a(n) for n = 1..2000</a>

%o (PARI) r=-1;forprime(p=2,10^12,v=valuation(p-1,2);if(v>r,print1(v,", ");r=v));

%o (Python)

%o from itertools import count, islice

%o from sympy import isprime

%o def A370607_gen(): # generator of terms

%o     a = 1

%o     while True:

%o         for q in count(a,a):

%o             if isprime(q+1):

%o                 yield (b:=q&-q).bit_length()-1

%o                 a = b<<1

%o                 break

%o A370607_list = list(islice(A370607_gen(),30)) # _Chai Wah Wu_, Feb 23 2024

%K nonn

%O 1,3

%A _Joerg Arndt_, Feb 23 2024

%E a(21)-a(67) from _Chai Wah Wu_, Feb 23 2024