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 A032917 Numbers having only digits 1 and 3 in their decimal representation. 14
 1, 3, 11, 13, 31, 33, 111, 113, 131, 133, 311, 313, 331, 333, 1111, 1113, 1131, 1133, 1311, 1313, 1331, 1333, 3111, 3113, 3131, 3133, 3311, 3313, 3331, 3333, 11111, 11113, 11131, 11133, 11311, 11313, 11331, 11333, 13111, 13113 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers n such that product of digits of n is a power of 3. - Vincenzo Librandi Aug 19 2016 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 MATHEMATICA Flatten[Table[FromDigits[#, 10]&/@Tuples[{1, 3}, n], {n, 5}]] (* Vincenzo Librandi, Jun 02 2012 *) PROG (Magma) [n: n in [1..14000] | Set(IntegerToSequence(n, 10)) subset {1, 3}]; // Vincenzo Librandi, Jun 02 2012 (PARI) for(n=1, 5, p=2*vector(n, i, 10^(n-i))~; forvec(d=vector(n, i, [1, 3]/2), print1(d*p, ", "))) \\ M. F. Hasler, Mar 10 2014 (Python) def a(n): return int(bin(n+1)[3:].replace('1', '3').replace('0', '1')) print([a(n) for n in range(1, 45)]) # Michael S. Branicky, May 13 2021 (Python) def A032917(n): return (int(bin(m:=n+1)[3:])<<1) + (10**(m.bit_length()-1)-1)//9 # Chai Wah Wu, Oct 13 2023 CROSSREFS CF. A020451 (primes). Sequence in context: A287348 A019374 A033680 * A006559 A023248 A199341 Adjacent sequences: A032914 A032915 A032916 * A032918 A032919 A032920 KEYWORD nonn,base AUTHOR Clark Kimberling EXTENSIONS Definition reworded by M. F. Hasler, Mar 10 2014 STATUS approved

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Last modified July 25 11:18 EDT 2024. Contains 374588 sequences. (Running on oeis4.)