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 A049345 n written in primorial base. 74
 0, 1, 10, 11, 20, 21, 100, 101, 110, 111, 120, 121, 200, 201, 210, 211, 220, 221, 300, 301, 310, 311, 320, 321, 400, 401, 410, 411, 420, 421, 1000, 1001, 1010, 1011, 1020, 1021, 1100, 1101, 1110, 1111, 1120, 1121, 1200, 1201, 1210, 1211, 1220, 1221, 1300, 1301, 1310, 1311 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Places reading from right have values (1, 2, 6, 30, 210, ...) = primorials. For n < 10 * 7# = 2100: a(n) = concatenation of n-th row in A235168 and for n > 0: A055642(a(n)) = A235224(n); for larger numbers the representation in A235168 is more appropriate. - Reinhard Zumkeller, Jan 05 2014 In the long run, numbers have fewer digits in the primorial base than in the factorial base (cf. A007623), since factorial(n) < n^n < primorial(n) for n > 12. However, the point where the digits become larger than 9 comes earlier: as soon as 10*7*5*3*2 = 2100 for the primorial base vs 10! = 3628800 in the factorial base. From there on, the representation using concatenation of digits written in decimal becomes ambiguous. - M. F. Hasler, Sep 22 2014 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..2099 MATHEMATICA Table[FromDigits@ IntegerDigits[n, MixedRadix[Reverse@ Prime@ Range@ 8]], {n, 0, 51}] (* Michael De Vlieger, Aug 23 2016, Version 10.2 *) PROG (Haskell) a049345 n | n < 2100  = read \$ concatMap show (a235168_row n) :: Int           | otherwise = error "ambiguous primorial representation" -- Reinhard Zumkeller, Jan 05 2014 (PARI) A049345(n, p=2) = if(n 9 would arise (n=10*7*5*3*2), thereafter the definition of the sequence is ambiguous. M. F. Hasler, Sep 22 2014 (Scheme) (define (A049345 n) (if (>= n 2100) (error "A049345: ambiguous primorial representation when n is larger than 2099:" n) (let loop ((n n) (s 0) (t 1) (i 1)) (if (zero? n) s (let* ((p (A000040 i)) (d (modulo n p))) (loop (/ (- n d) p) (+ (* t d) s) (* 10 t) (+ 1 i))))))) ;; Antti Karttunen, Aug 26 2016 (Python) from sympy import nextprime def a(n, p=2):     if n>2099: print("Error! Ambiguous primorial representation when n is larger than 2099")     else: return n if n

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Last modified January 21 13:57 EST 2021. Contains 340351 sequences. (Running on oeis4.)