A381921 Factorial numbers whose Hamming weight is also a factorial number.

1, 2, 6, 24, 5040, 40320, 362880, 1982608315404440064116146708361898137544773690227268628106279599612729753600000000000000, 126886932185884164103433389335161480802865516174545192198801894375214704230400000000000000

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Formula

a(n) = A000142(A381922(n)).

Example

k = 7:  A000120(A000142(7)) = 6, 6 is from A000142, thus 7! is a term.

Mathematica

With[{f = Range[100]!}, Select[f, MemberQ[f, DigitCount[#, 2, 1]] &]] (* Amiram Eldar, Mar 10 2025 *)

Crossrefs

Cf. A000120, A000142, A381922.

Sequence in context: A089718 A123150 A086591 * A173609 A294945 A353363

Adjacent sequences: A381914 A381915 A381916 * A381922 A381923 A381925

Keyword

nonn,base,new

Author

Ctibor O. Zizka, Mar 10 2025

Status

approved