OFFSET
1,1
COMMENTS
A004601 is the concatenation of binary digits of the terms written in base 2.
EXAMPLE
A004601( expansion of Pi in base 2) :
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.... ->
1,1,0,0 | 1,0,0 | 1,0,0,0,0 | 1,1,1,1,1,1,0 | 1,1,0 | 1,0 | ... ->
1100 | 100 |10000 | 1111110 |110 |10 | 10 | ... (in base 2) ->
12 , 4, 16, 126, 6, 2, 2, ... (in base 10) .
MATHEMATICA
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 *)
PROG
(Python)
import gmpy2
pi = gmpy2.const_pi(precision=310) # increase precision for more terms
h = "{0:A}".format(pi)[2:-5].replace(".", "")
b = bin(int(h, 16))[2:]
splitb = b.replace("01", "0, 1").split(", ")
print([int(t, 2) for t in splitb[:-1]]) # Michael S. Branicky, Dec 04 2021
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Philippe Deléham, Nov 09 2011
STATUS
approved