%I #39 Sep 05 2024 15:39:11
%S 2,7,12,5468,10924,5597880,16777229
%N Leading power of 4 in A230638.
%C a(9) = ( 4^5468 + 2*4^12 + 39 ) / 3.
%C a(10) = 4^5468 + 13.
%C a(11) = ( 4^10924 + 2*4^5468 + 16407 ) / 3.
%C a(12) = 4^10924 + 10925
%C a(13) = ( 4^5597880 + 3*4^10924 + 32793 ) / 3.
%C a(14) = ( 2*4^5597880 + 32812 ) / 3.
%C a(15) = ( 4^16777229 + 4^5597880 + 2*4^12 + 16427 ) / 3.
%C a(16) = ( 2*4^16777229 + 4^13 + 42 ) / 3.
%H Max Alekseyev, <a href="/A230637/a230637_2.txt">Table n, expression for a(n) for n=2..100</a>
%H Max A. Alekseyev and N. J. A. Sloane, <a href="https://arxiv.org/abs/2112.14365">On Kaprekar's Junction Numbers</a>, arXiv:2112.14365, 2021; Journal of Combinatorics and Number Theory 12:3 (2022), 115-155.
%H <a href="/index/Coi#Colombian">Index entries for Colombian or self numbers and related sequences</a>
%Y Cf. A230638.
%Y Related base-4 sequences: A053737, A230631, A230632, A010064, A230633, A230634, A230635, A230636, A230637, A230638, A010065 (trajectory of 1)
%K nonn,base
%O 2,1
%A _N. J. A. Sloane_, Oct 31 2013
%E Terms a(8) onward from _Max Alekseyev_, Oct 31 2013