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 A257680 Characteristic function for A256450: 1 if there is at least one 1-digit present in the factorial representation of n (A007623), otherwise 0. 19
 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0 LINKS Antti Karttunen, Table of n, a(n) for n = 0..10080 FORMULA a(0) = 0; for n >= 1, if A099563(n) = 1, then a(n) = 1, otherwise a(n) = a(A257687(n)). Other identities: a(2n+1) = 1 for all n. [Because all odd numbers end with digit 1 in factorial base.] PROG (Scheme) (define (A257680 n) (let loop ((n n) (i 2)) (cond ((zero? n) 0) ((= 1 (modulo n i)) 1) (else (loop (floor->exact (/ n i)) (+ 1 i)))))) ;; As a recurrence utilizing memoizing definec-macro: (definec (A257680 n) (cond ((zero? n) 0) ((= 1 (A099563 n)) 1) (else (A257680 (A257687 n))))) (Python) def a007623(n, p=2): return n if n

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Last modified September 17 16:00 EDT 2021. Contains 347478 sequences. (Running on oeis4.)