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

1,2

Comments

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

Links

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

Formula

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

Example

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

Prog

(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

Crossrefs

Cf. A065760, A065447.

Sequence in context: A010791 A145169 A193210 * A374021 A002832 A233151

Adjacent sequences: A065758 A065759 A065760 * A065762 A065763 A065764

Keyword

base,easy,nonn

Author

Lior Manor, Nov 18 2001

Status

approved