A135728 Record indices of A135727(n) = max{ A001281^k(n);k=0,1,2,3... } (3x-1 problem).

0, 1, 3, 5, 9, 17, 33, 65, 129, 153, 321, 1425, 1601, 1889, 3393, 4097, 6929, 8193, 10497, 11025, 18273, 28161, 74585, 85265, 149345, 337761, 558341, 839429, 1022105, 1467393, 7932689, 8612097, 23911397, 58882625, 75567105, 293056017

Offset

1,3

Comments

This gives indices n for which A135727(n) is larger than all preceding values of that sequence. As in A135727(n), we include the fixed point 0 in the domain of A001281. Obviously, many but not all entries are of the form 2^k+1 and not all of such numbers are in the sequence (e.g. 257, 1025, 2049 are missing). Is there a simple way of characterizing the exceptions?

Links

Table of n, a(n) for n=1..36.

Prog

(PARI) A135728(Nmax=10^4)=local(m=-1); for(n=0, Nmax, if(m+0<m=max(m, A135727(n)), print1(n", ")))

Crossrefs

Cf. A001281, A037084, A039500-A039505, A135727-A135730. A006370, A006577.

Sequence in context: A213005 A171856 A205537 * A083318 A127904 A048578

Adjacent sequences: A135725 A135726 A135727 * A135729 A135730 A135731

Keyword

nonn

Author

M. F. Hasler, Nov 26 2007

Extensions

a(19)-a(36) from Donovan Johnson, Nov 06 2010

Status

approved