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A007089
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Numbers in base 3.
(Formerly M1960)
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326
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0, 1, 2, 10, 11, 12, 20, 21, 22, 100, 101, 102, 110, 111, 112, 120, 121, 122, 200, 201, 202, 210, 211, 212, 220, 221, 222, 1000, 1001, 1002, 1010, 1011, 1012, 1020, 1021, 1022, 1100, 1101, 1102, 1110, 1111, 1112, 1120, 1121, 1122, 1200, 1201, 1202, 1210, 1211
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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COMMENTS
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Nonnegative integers with no decimal digit > 2. Thus nonnegative integers in base 10 whose quadrupling by normal addition or multiplication requires no carry operation. - Rick L. Shepherd, Jun 25 2009
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Eric Weisstein's World of Mathematics, Ternary.
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FORMULA
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a(0)=0, a(n) = 10*a(n/3) if n==0 (mod 3), a(n) = a(n-1) + 1 otherwise. - Benoit Cloitre, Dec 22 2002
a(n) = 10*a(floor(n/3)) + (n mod 3) if n > 0, a(0) = 0. - M. F. Hasler, Feb 15 2023
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MAPLE
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A007089 := proc(n) option remember;
if n <= 0 then 0
else
if (n mod 3) = 0 then 10*procname(n/3) else procname(n-1) + 1 fi
fi end:
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MATHEMATICA
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Table[ FromDigits[ IntegerDigits[n, 3]], {n, 0, 50}]
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PROG
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(PARI) a(n)=if(n<1, 0, if(n%3, a(n-1)+1, 10*a(n/3)))
(Haskell)
a007089 0 = 0
a007089 n = 10 * a007089 n' + m where (n', m) = divMod n 3
(Python)
n, s = divmod(n, 3); t = 1
while n: n, r = divmod(n, 3); t *= 10; s += r*t
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CROSSREFS
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Cf. A000042, A007088, A007090, A007091, A007092, A007093, A007094, A007095, A077267, A062756, A081603, A081604, A054635, A003137.
Primes when read as if in base 10: A036954.
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KEYWORD
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base,nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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