A264619 a(0) = 1; for n>0, working in binary, write n followed by 1 then n-reversed (including leading zeros); show result in base 10.

1, 7, 21, 31, 73, 93, 107, 127, 273, 313, 341, 381, 403, 443, 471, 511, 1057, 1137, 1193, 1273, 1317, 1397, 1453, 1533, 1571, 1651, 1707, 1787, 1831, 1911, 1967, 2047, 4161, 4321, 4433, 4593, 4681, 4841, 4953, 5113, 5189, 5349, 5461, 5621, 5709, 5869, 5981, 6141, 6211, 6371, 6483, 6643, 6731, 6891, 7003, 7163, 7239

Offset

0,2

Comments

a(n) = A062383(n) + A264618(n); n>0: A070939(a(n)) = 2*A070939(n)+1; A000120(a(n)) = 2*A000120(n)+1; n>0: A023416(a(n)) = 2*A023416(n). - Reinhard Zumkeller, Dec 01 2015

Links

N. J. A. Sloane, Table of n, a(n) for n = 0..32767

Example

1 -> 111 = 7,
10 -> 10101 = 21,
11 -> 11111 = 31,
100 -> 1001001 = 73,
...

Mathematica

A264619[0] = 1; A264619[n_] := FromDigits[Join[#, {1}, Reverse[#]], 2]&@ IntegerDigits[n, 2] (* JungHwan Min, Dec 01 2015 *)
bnr[n_]:=Module[{idn2=IntegerDigits[n, 2]}, FromDigits[Join[idn2, {1}, Reverse[ idn2]], 2]]; Join[{1}, Array[bnr, 60]] (* Harvey P. Dale, Nov 05 2017 *)

Prog

(Haskell)
a264619 0 = 1
a264619 n = foldr (\b v -> 2 * v + b) 0 $ (reverse bs ++ (1 : bs))
            where bs = map fromIntegral $ a030308_row n
-- Reinhard Zumkeller, Dec 01 2015

Crossrefs

Cf. A006995, A048701 (n followed by n-reversed), A264618.

First differences: A265029.

Cf. A007088, A030308, A000120, A023416, A062383, A070939.

Sequence in context: A297178 A325553 A032639 * A015729 A271972 A001485

Adjacent sequences: A264616 A264617 A264618 * A264620 A264621 A264622

Keyword

nonn

Author

N. J. A. Sloane, Nov 30 2015

Status

approved