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 A032925 Numbers whose set of base-4 digits is a subset of {1,2}. 10
 1, 2, 5, 6, 9, 10, 21, 22, 25, 26, 37, 38, 41, 42, 85, 86, 89, 90, 101, 102, 105, 106, 149, 150, 153, 154, 165, 166, 169, 170, 341, 342, 345, 346, 357, 358, 361, 362, 405, 406, 409, 410, 421, 422, 425, 426, 597, 598, 601, 602, 613, 614, 617, 618, 661, 662, 665 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Intersection of A023705 and A023717; A179888 is the intersection of this sequence and A053754. - Reinhard Zumkeller, Jul 31 2010 LINKS R. Zumkeller, Table of n, a(n) for n = 1..1000 FORMULA a(2n) = 4a(n-1) + 2, a(2n+1) = 4a(n) + 1. - Ralf Stephan, Oct 07 2003, corrected by R. J. Mathar, Sep 07 2016 MAPLE A032925 := proc(n) option remember; if n <= 2 then n; else if type(n, 'even') then 2+4*procname(n/2-1) ; else 1+4*procname(floor(n/2)) ; end if; end if; end proc: seq(A032925(n), n=1..100) ; # R. J. Mathar, Sep 07 2016 MATHEMATICA Flatten[Table[FromDigits[#, 4]&/@Tuples[{1, 2}, n], {n, 5}]] (* Vincenzo Librandi, Jun 05 2012 *) PROG (Magma) [n: n in [1..1000] | Set(IntegerToSequence(n, 4)) subset {1, 2}]; // Vincenzo Librandi, Jun 05 2012 (Haskell) import Data.List (transpose) a032925 n = a032925_list !! (n-1) a032925_list = 1 : 2 : (concat \$ transpose [map (+ 1) fs, map (+ 2) fs]) where fs = map (* 4) a032925_list -- Reinhard Zumkeller, Apr 18 2015 (C) uint32_t a_next(uint32_t a_n) { uint32_t t = (a_n + 0x55555556) ^ 0x55555555; return (a_n - t) & t; } /* Falk Hüffner, Jan 22 2022 */ CROSSREFS Cf. A023705, A023717, A179888, A053754. Sequence in context: A078632 A309242 A122701 * A244749 A166087 A333545 Adjacent sequences: A032922 A032923 A032924 * A032926 A032927 A032928 KEYWORD nonn,base,easy AUTHOR Clark Kimberling STATUS approved

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Last modified November 30 21:14 EST 2023. Contains 367462 sequences. (Running on oeis4.)