A065761 Concatenation of increasing number of alternating digits in base 2, starting with 0.

0, 3, 24, 399, 12768, 817215, 104603520, 26778501375, 13710592704000, 14039646928897023, 28753196910381103104, 117773094544920998318079, 964797190511992818221703168, 15807237169348490333744384720895

Offset: 1

Author

Lior Manor, Nov 18 2001

Keywords

• base
• easy
• nonn

Comments

The first 5 terms in base 2 are 0, (0)11, (0)11000, (0)110001111, (0)11000111100000.

Examples

			a(5) = 12768 is formed by appending 0 five times (00000) to a(4) in base 2: (0)11000111100000.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 1..50

Crossrefs

Cf. A065760, A065447.

Programs

PARI

baseI(x, b)= { local(d, e=0, f=1); while (x>0, d=x-10*(x\10); x\=10; e+=d*f; f*=b); return(e) } { c=1; for (n=1, 50, if (n==1, a=0; b=0, c=c*10 + 1; if (n%2, d=0, d=c); b=b*10^n + d; a=baseI(b, 2)); write("b065761.txt", n, " ",a) ) } \\ Harry J. Smith, Oct 30 2009

Formula

a(1) = 0; a(n+1) = append n+1 0's or 1's (alternately) to a(n).