%I
%S 12,4,16,126,6,2,2,8,8,16,2,6,8,48,8,6,4,24,4,24,12,24,2,8,2,896,6,
%T 224,28,6,8,4,2,4,64,4,4,224,8,8,2,4,12,124,24,14,256,32,2,14,62,2,4,
%U 24,14,24,4,28,6,12,8,4,2,8,2,4,2,32,16,60,24,56,6
%N Related to the expansion of Pi in base 2 (A004601).
%C A004601 is the concatenation of binary digits of the terms written in base 2.
%e A004601( expansion of Pi in base 2) :
%e 1,1,0,0,1,0,0,1,0,0,0,0,1,1,1,1,1,1,0,1,1,0,1,0,1,0.... >
%e 1,1,0,0  1,0,0  1,0,0,0,0  1,1,1,1,1,1,0  1,1,0  1,0  ... >
%e 1100  100 10000  1111110 110 10  10  ... (in base 2) >
%e 12 , 4, 16, 126, 6, 2, 2, ... (in base 10) .
%t f[{a_, b_}] := (2^a  1)*2^b; f /@ Partition[Length /@ Split[First[RealDigits[π, 2, 10^3]]], 2] (* _T. D. Noe_, Nov 09 2011 *)
%o (Python)
%o import gmpy2
%o pi = gmpy2.const_pi(precision=310) # increase precision for more terms
%o h = "{0:A}".format(pi)[2:5].replace(".", "")
%o b = bin(int(h, 16))[2:]
%o splitb = b.replace("01", "0,1").split(",")
%o print([int(t, 2) for t in splitb[:1]]) # _Michael S. Branicky_, Dec 04 2021
%Y Cf. A004601, A007088.
%K easy,nonn,base
%O 1,1
%A _Philippe Deléham_, Nov 09 2011
