A261220 Ranks of involutions in permutation orderings A060117 and A060118.

0, 1, 2, 4, 6, 7, 12, 16, 18, 20, 24, 25, 26, 28, 48, 49, 60, 66, 72, 76, 78, 90, 96, 98, 102, 108, 120, 121, 122, 124, 126, 127, 132, 136, 138, 140, 240, 241, 242, 244, 288, 289, 312, 316, 336, 338, 360, 361, 372, 378, 384, 385, 432, 450, 456, 468, 480, 484, 486, 498, 504, 508, 528, 546, 576, 582, 600, 602, 606, 612, 624, 626, 648, 660, 672, 678, 720, 721

Offset

0,3

Comments

From Antti Karttunen, Aug 17 2016: (Start)

Intersection of A275804 and A276005. In other words, these are numbers in whose factorial base representation (A007623, see A260743) there does not exist any such pair of nonzero digits d_i and d_j in positions i and j that either (i - d_i) = j or (i - d_i) = (j - d_j) would hold. Here one-based indexing is used so that the least significant digit at right is in position 1.

(End)

Links

Antti Karttunen, Table of n, a(n) for n = 0..1000

Index entries for sequences related to factorial base representation

Prog

(Scheme, three variants, all requiring Antti Karttunen's IntSeq-library)
(define A261220 (ZERO-POS 0 0 (lambda (n) (+ (A275947 n) (A276007 n)))))
(define A261220 (MATCHING-POS 0 0 (lambda (n) (>= 2 (A275803 n)))))
(define A261220 (MATCHING-POS 0 0 (lambda (n) (>= 2 (A060131 n)))))

Crossrefs

Intersection of A275804 and A276005.

Same sequence shown in factorial base: A260743.

Cf. A060117, A060118, A275947, A276007.

Positions of zeros in A261219.

Positions of 1 and 2's in A060131 and A275803.

Subsequence: A060112.

Cf. also A014489.

Sequence in context: A070317 A138398 A086781 * A272589 A191191 A191190

Adjacent sequences: A261217 A261218 A261219 * A261221 A261222 A261223

Keyword

nonn,base

Author

Antti Karttunen, Aug 26 2015

Status

approved