A145015 - OEIS

%I #2 Jun 01 2010 03:00:00

%S 1,3,1,3,3,5,3,1,1,3,1,7,7,1,3,5,3,13,7,1,3,1,1,3,3,1,1,3,1,7,3,1,1,3,

%T 1,7,1,15,15,1,7,1,3,5,7,1,3,5,3,13,7,1,3,5,3,13,3,29,15,1,7,1,3,1,1,

%U 3,7,1,3,1,1,3,3,1,1,3,1,7,7,1,3,1,1,3,3,1,1,3,1,7,3,1,1,3,1,7,1,15,7,1

%N Run lengths in A037861 having the same sign.

%C a(n) seems (conjecture) to contain only the numbers 2^n - 1 (for n>=1) and 2^n - 3 (for n>=3)

%e A037861 is: 1,-1,0,-2,1,-1,-1,-3,2,0,0,-2,0,-2,-2,-4,3, ... so sign is +,-,0,-,+,-,-,-,+,0,0,-,0,-,-,-,+, ... thus sequence is 1,3,1,3,3,5, ...

%Y Cf. A037861.

%K base,nonn

%O 0,2

%A Denis Boigelot (dboigelo(AT)ulb.ac.be), Sep 29 2008