OFFSET
0,4
COMMENTS
Equally: main diagonal of A261097.
For permutation p, which has rank n in permutation list A055089 (A195663), a(n) gives the rank of the "square" of that permutation (obtained by composing it with itself as: q(i) = p(p(i))) in the same list. Thus zeros (which mark the identity permutation, with rank 0) occur at positions where the permutations of A055089/A195663 are involutions, listed by A014489.
LINKS
Antti Karttunen, Table of n, a(n) for n = 0..5040
FORMULA
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Aug 26 2015
STATUS
approved