A090080 - OEIS

A090080

In binary expansion of n-th prime: reduce contiguous blocks of 0's to 0 and contiguous blocks of 1's to 1.

%I #3 Mar 30 2012 18:50:42

%S 2,1,5,1,5,5,5,5,5,5,1,21,21,21,5,21,5,5,5,5,21,5,21,21,5,21,5,21,21,

%T 5,1,5,21,21,85,21,21,21,21,85,21,85,5,5,21,5,21,5,5,21,21,5,5,5,5,5,

%U 21,5,85,21,21,85,21,21,21,21,85,85,85,85,21,21,21,85,21,5,21,21,21

%N In binary expansion of n-th prime: reduce contiguous blocks of 0's to 0 and contiguous blocks of 1's to 1.

%C a(n) = A090079(A000040(n)).

%e A000040(25)=97 -> '1100001' -> [11][0000][1] -> [1][0][1] ->

%e '101' -> 5=a(25).

%Y Cf. A004676.

%K nonn,base

%O 1,1

%A _Reinhard Zumkeller_, Nov 20 2003