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A065760 Concatenation of increasing number of alternating digits in base 2, starting with 1. 3
1, 4, 39, 624, 19999, 1279936, 163831935, 41940975360, 21473779384831, 21989150090066944, 45033779384457103359, 184458360358736295358464, 1511082888058767731576545279, 24757582037954850514150117851136 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

a(n) = a(n-1) * 2^n if n is even, (a(n-1) + 1) * 2^n - 1 if n is odd. - Franklin T. Adams-Watters, Sep 18 2012

EXAMPLE

a(5) = 19999 is formed by appending 1 five times (11111) to a(4) in base 2: 100111000011111.

MATHEMATICA

With[{nn=20}, Table[FromDigits[Flatten[Take[Table[Table[If[EvenQ[n], 0, 1], {n}], {n, nn}], j]], 2], {j, nn}]] (* Harvey P. Dale, Sep 09 2012 *)

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=1; b=1, c=c*10 + 1; if (n%2, d=c, d=0); b=b*10^n + d; a=baseI(b, 2)); write("b065760.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 30 2009

CROSSREFS

Decimal version of A065447. Cf. A065761.

Sequence in context: A189489 A178920 A066399 * A132612 A129463 A299426

Adjacent sequences:  A065757 A065758 A065759 * A065761 A065762 A065763

KEYWORD

base,easy,nonn

AUTHOR

Lior Manor Nov 18 2001

STATUS

approved

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Last modified October 15 13:06 EDT 2019. Contains 328030 sequences. (Running on oeis4.)