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 A179888 Starting with a(1)=2: if m is a term then also 4*m+1 and 4*m+2. 8
 2, 9, 10, 37, 38, 41, 42, 149, 150, 153, 154, 165, 166, 169, 170, 597, 598, 601, 602, 613, 614, 617, 618, 661, 662, 665, 666, 677, 678, 681, 682, 2389, 2390, 2393, 2394, 2405, 2406, 2409, 2410, 2453, 2454, 2457, 2458, 2469, 2470, 2473, 2474, 2645, 2646, 2649 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 0 -> 01 and 1 -> 10 in binary representation of n; intersection of A032925 and A053754; subsequence of A063037; A000120(a(n))=A023416(a(n))=A070939(n); A070939(a(n))=2*A070939(n). LINKS R. Zumkeller, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Quaternary FORMULA a(n) = 4*a(floor(n/2)) + n mod 2 + 1 for n>1; a(n)=SUM((bit(k)+1)*4^k: 0<=k<=L), where bit() and L such that n=SUM(bit(k)*2^k: 0<=k<=L). EXAMPLE __ n | __ bin(n) || ___ bin(a(n)) | base-4(a(n)) | __ a(n) -----|-----------||---------------|--------------|--------- .. 1 | ....... 1 || .......... 10 | .......... 2 | ..... 2; .. 2 | ...... 10 || ........ 1001 | ......... 21 | ..... 9; .. 3 | ...... 11 || ........ 1010 | ......... 22 | .... 10; .. 4 | ..... 100 || ...... 100101 | ........ 211 | .... 37; .. 5 | ..... 101 || ...... 100110 | ........ 212 | .... 38; .. 6 | ..... 110 || ...... 101001 | ........ 221 | .... 41; .. 7 | ..... 111 || ...... 101010 | ........ 222 | .... 42; .. 8 | .... 1000 || .... 10010101 | ....... 2111 | ... 149; .. 9 | .... 1001 || .... 10010110 | ....... 2112 | ... 150; . 10 | .... 1010 || .... 10011001 | ....... 2121 | ... 153; . 11 | .... 1011 || .... 10011010 | ....... 2122 | ... 154; . 12 | .... 1100 || .... 10100101 | ....... 2211 | ... 165; . 13 | .... 1101 || .... 10100110 | ....... 2212 | ... 166; . 14 | .... 1110 || .... 10101001 | ....... 2221 | ... 169; . 15 | .... 1111 || .... 10101010 | ....... 2222 | ... 170; . 16 | ... 10000 || .. 1001010101 | ...... 21111 | ... 597; . 17 | ... 10001 || .. 1001010110 | ...... 21112 | ... 598; . 18 | ... 10010 || .. 1001011001 | ...... 21121 | ... 601; . 19 | ... 10011 || .. 1001011010 | ...... 21122 | ... 602; . 20 | ... 10100 || .. 1001100101 | ...... 21211 | ... 613. MATHEMATICA Union@ Flatten@ NestList[ {4 # + 1, 4 # + 2} &, 2, 5] (* Robert G. Wilson v, Aug 16 2011 *) PROG (Haskell) a179888 n = a179888_list !! (n-1) a179888_list = 2 : f a179888_list where   f (x:xs) = x' : x'' : f (xs ++ [x', x'']) where x' = 4*x+1; x'' = x' + 1 -- Reinhard Zumkeller, Oct 29 2011 CROSSREFS Cf. A132679, A196168. Sequence in context: A290592 A058551 A119183 * A073082 A300129 A191401 Adjacent sequences:  A179885 A179886 A179887 * A179889 A179890 A179891 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jul 31 2010 STATUS approved

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Last modified March 21 01:18 EDT 2019. Contains 321356 sequences. (Running on oeis4.)