A354150 - OEIS

%I #34 Aug 24 2022 01:19:26

%S 1,2,5,11,23,95,191,383,1535,6143,24575,49151,196607,786431,3145727,

%T 12582911,50331647,201326591,805306367

%N Index of 2^n in A090252, or -1 if 2^n does not appear.

%C It is conjectured (see A090252) that the indices of even terms in A090252 are {3*2^i-1, i >= 0} (A083329), so the positive terms of the present sequence should be a subsequence of A083329.

%C For n = 1,...,18, the terms are 3*2^k - 1 for k = 0,1,2,3,5,6,7,9,11,13,14,16,18,20,22,24,26,28. Will the formula a(n) = 3*2^(2*n-8)-1 hold for all n >= 11? This appears to be yet another example of the influence of A029744 on A090252 and A354691.- _N. J. A. Sloane_, Aug 24 2022

%Y Cf. A090252, A083329, A354148, A354149, A354255 (even terms in A090252).

%Y See also A029744, A354169.

%K nonn,more

%O 0,2

%A _N. J. A. Sloane_, May 26 2022

%E a(10) from _Michael S. Branicky_, May 27 2022

%E a(11)-a(14) from _Michael S. Branicky_, Jun 01 2022 using gzipped b-file at A090252

%E a(15)-a(18) from _Jinyuan Wang_, Jul 15 2022