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A347208
Number of permutations of [n] that are in the same position in A030298 as they are in A098281.
0
1, 2, 3, 3, 3, 10, 5, 4, 5, 13, 3, 6, 5
OFFSET
1,2
EXAMPLE
For n = 7 the a(7) = 5 permutations are 1234567, 1234576, 1236745, 6574231, 7654321, which are in positions 1, 2, 17, 4198, 5040 respectively in both sequences A030298 and A098281.
MATHEMATICA
perms[n_] := perms[n] = If[n == 1, {{1}}, Flatten[Table[Insert[#, n, pos], {pos, -1, -n, -1}]& /@ perms[n-1], 1]];
a[n_] := Count[Transpose@{perms[n], Permutations[Range[n]]}, {p_, p_}];
Table[a[n], {n, 1, 10}] (* Jean-François Alcover, Sep 02 2021 *)
CROSSREFS
Sequence in context: A334579 A199457 A361378 * A210483 A022296 A013069
KEYWORD
nonn,more
AUTHOR
William Chang, Aug 23 2021
STATUS
approved