|
%I #4 Mar 31 2012 14:02:29
%S 0,21,3613,3771,3906,3929,3783
%N Atavistic Index Sequence to A089840 computed for SPINE.
%C Recursive transformation SPINE for Catalan bijections has a well-defined inverse (see the definition & comments at A122203). For all Catalan bijections in A089840 that inverse produces a bijection which is itself in A089840. This sequence gives the indices to those positions where each ("primitive", non-recursive bijection) of A089840(n) occurs "atavistically" amongst the more complex recursive bijections in A122203. I.e. A122203(a(n)) = A089840(n). Similarly, other "atavistic forms" resurface as: A122288(a(n)) = A122202(n), A122285(a(n)) = A122204(n) and A122201(a(n)) = A122283(n). See also comments at A153832.
%C Other known terms: a(17)-a(44): 65352, 65359, 65604, 65739, 251, 1656303, 1656426, 1656552, 1656628, 1656479, 1661655, 1661816, 1666720, 1684006, 1684221, 1667042, 1667007, 1684152, 1661799, 1661676, 1666759, 1684081, 1684437, 1667151, 1684509, 1667187, 1661961, 1661944.
%H A. Karttunen, <a href="/A089839/a089839.c.txt">C-program for computing the initial terms of this sequence</a>
%F a(n) = A089839bi(A153834(A089843(n)),n)
%Y Cf. A153832, A089839.
%K nonn
%O 0,2
%A _Antti Karttunen_, Jan 07 2009
|
