A163894 The least i for which A163355^n(i) is not equal to i, 0 if no such i exists, i.e., when A163355^n = A001477.

0, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4, 2, 33, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4, 2, 76, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4, 2, 33, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4, 2, 76, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4, 2, 33, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4, 2, 390, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4, 2, 33, 2, 4, 2, 4, 2, 24, 2, 4, 2, 4

Offset

0,2

Comments

A163355^n means n-fold application of A163355, i.e., A163355^2 = A163905, A163355^3 = A163915. By convention A163355^0 = A001477.

Links

A. Karttunen, Table of n, a(n) for n = 0..4095

Maple

A163894 := proc(n)
    local i, a355, a, itr ;
    if n = 0 then
        return 0 ;
    end if;
    a := 0 ;
    for i from 0 do
        a355 := A163355(i) ;
        for itr from 2 to n do
            a355 := A163355(a355) ;
        end do:
        if a355 <> i then
            return i ;
        end if;
    end do:
end proc:
seq(A163894(n), n=0..100) ; # R. J. Mathar, Nov 22 2023

Prog

(MIT Scheme:)
(define (A163894 n) (if (zero? n) 0 (let loop ((i 1) (n-th_power (compose-fun-to-n-th-power a163355 n))) (cond ((not (= i (n-th_power i))) i) (else (loop (1+ i) n-th_power))))))
(define (compose-fun-to-n-th-power fun n) (cond ((zero? n) (lambda (x) x)) (else (lambda (x) (fun ((compose-fun-to-n-th-power fun (- n 1)) x))))))

Crossrefs

See A163890, A163895, A163896.

Sequence in context: A274708 A280638 A333725 * A307095 A032059 A074075

Adjacent sequences: A163891 A163892 A163893 * A163895 A163896 A163897

Keyword

nonn

Author

Antti Karttunen, Sep 19 2009

Status

approved