OFFSET
1,1
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
EXAMPLE
n=10: GCD of backward written powers of 2 is GCD(4201, 8402) = 4201 = a(10).
MATHEMATICA
rd[x_] :=FromDigits[Reverse[IntegerDigits[x]]] Table[GCD[rd[2^w], rd[2^(w+1)]], {w, 1, 100}]
GCD[IntegerReverse[#[[1]]], IntegerReverse[#[[2]]]]&/@ Partition[ 2^Range[110], 2, 1] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 24 2017 *)
PROG
(PARI)
rev(n) = subst(Polrev(digits(n)), 'x, 10); \\ These two functions from Charles R Greathouse IV, Oct 20 2014
A004094(n) = rev(2^n);
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Labos Elemer, Jan 25 2005
STATUS
approved