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A079498
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Numbers whose sum of digits in base b gives 0 (mod b), for b = 3.
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3
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0, 5, 7, 11, 13, 15, 19, 21, 26, 29, 31, 33, 37, 39, 44, 45, 50, 52, 55, 57, 62, 63, 68, 70, 74, 76, 78, 83, 85, 87, 91, 93, 98, 99, 104, 106, 109, 111, 116, 117, 122, 124, 128, 130, 132, 135, 140, 142, 146, 148, 150, 154, 156, 161, 163, 165, 170, 171, 176, 178, 182, 184
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OFFSET
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1,2
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COMMENTS
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In base 2 this gives the "Evil Numbers" (cf. A001969). One may conjecture that in base b the asymptotic slope will be b and asymptotic density 1/b for each result (mod b). Cases b=31 or b=61 gave considerable number of primes on the sequence.
Proof of this conjecture: in general, the sequence d with terms d(n) = sum of digits of n written in base b (mod b) is a fixed point of the generalized Thue-Morse morphism 0->01..b-1, 1->12..0, etc. See A053839 for the case b=4. It follows directly from this that all symbols have asymptotic density 1/b, and therefore that the positional sequences all have asymptotic slope b. - Michel Dekking, Apr 18 2019
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LINKS
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EXAMPLE
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83 is a term since 83 = (1,0,0,0,2)_3 and 1 + 0 + 0 + 0 + 2 = 3 == 0 (mod 3).
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MATHEMATICA
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Ev = Function[{b, x}, vx = IntegerDigits[x, b]; Mod[Apply[Plus, vx], b]]; Seq = Function[{b, n}, Flatten[Position[Table[Ev[b, k], {k, 0, n}], 0]] - 1]; sb = Seq[3, 1000]
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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EXTENSIONS
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a(1) = 0 inserted and offset corrected by Amiram Eldar, Jan 05 2020
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STATUS
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approved
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