A147540 Numbers whose binary representation is the concatenation of 2n-1 digits 1, n digits 0 and 2n-1 digits 1.

5, 231, 7967, 260223, 8372735, 268306431, 8588894207, 274869551103, 8796026044415, 281474440364031, 9007194961870847, 288230341800361983, 9223371762010423295, 295147902980463788031, 9444732948147641253887

Offset

1,1

Comments

a(n) is the number whose binary representation is A138826(n).

Links

G. C. Greubel, Table of n, a(n) for n = 1..660

Formula

From R. J. Mathar, Nov 09 2008: (Start)

a(n) = 2^(5*n-2) - 2^(3*n-1) + 2^(2*n-1) - 1.

G.f.: x*(5 +6*x -128*x^2 +768*x^3)/((1-x)*(1-4*x)*(1-8*x)*(1-32*x)). (End)

Maple

seq( 2^(5*n-2) -2^(3*n-1) +2^(2*n-1) -1, n=1..20); # G. C. Greubel, Jan 12 2020

Mathematica

Table[FromDigits[Join[Table[1, {2n-1}], Table[0, {n}], Table[1, {2n-1}]], 2], {n, 15}] (* Stefan Steinerberger, Nov 11 2008 *)

Prog

(PARI) vector(20, n, 2^(5*n-2) -2^(3*n-1) +2^(2*n-1) -1) \\ G. C. Greubel, Jan 12 2020
(Magma) [2^(5*n-2) -2^(3*n-1) +2^(2*n-1) -1: n in [1..20]]; // G. C. Greubel, Jan 12 2020
(Sage) [2^(5*n-2) -2^(3*n-1) +2^(2*n-1) -1 for n in (1..20)] # G. C. Greubel, Jan 12 2020
(GAP) List([1..20], n-> 2^(5*n-2) -2^(3*n-1) +2^(2*n-1) -1); # G. C. Greubel, Jan 12 2020

Crossrefs

Cf. A138826.

Sequence in context: A355877 A065757 A157776 * A187366 A176898 A274996

Adjacent sequences: A147537 A147538 A147539 * A147541 A147542 A147543

Keyword

base,easy,nonn

Author

Omar E. Pol, Nov 06 2008

Extensions

More terms from R. J. Mathar and Stefan Steinerberger, Nov 11 2008

Status

approved