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

Author

N. J. A. Sloane, Nov 30 2015

Keywords

• nonn

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

Examples

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

Links

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

Crossrefs

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

First differences: A265029.

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

Programs

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

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 *)