A095900 a(n) = A004001(10^n).

1, 6, 57, 510, 5373, 53505, 510403, 5247173, 52736107, 511172800, 5189628970, 52334438874, 511861449132, 5150236044255, 52074775905991, 512279427101305, 5118687220533539, 51879201305335167, 512519244788358058

Offset

0,2

Comments

a(n)/n -> 10^n/(2*n). [Corrected by Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007]

Links

Herman Jamke, Table of n, a(n) for n = 0..30

C. L. Mallows, Conway's challenge sequence, Amer. Math. Monthly, 98 (1991), 5-20. See comments on formula due to G. Phillips on page 18.

Mathematica

a[1] = a[2] = 1; a[n_] := a[n] = a[a[n - 1]] + a[n - a[n - 1]]; Do[ a[n], {n, 1000000}]; Table[ a[10^n], {n, 0, 6}]

Prog

(PARI) print1("1, "); for(k=1, 30, n=10^k; row=floor(log(n)/log(2)); col=1; s=0; a=0; while(s<n, for(j=col, row+1, if(j>1, smd=binomial(row, j-2), smd=2^row); if((s+smd)>n, col=j-1; row=row-1; break, s+=smd; if(j>1, a+=binomial(row-1, j-2), a+=2^(row-1))))); print1(a", ")) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007

Crossrefs

Cf. A004001.

Sequence in context: A229280 A124546 A144070 * A161434 A332620 A371521

Adjacent sequences: A095897 A095898 A095899 * A095901 A095902 A095903

Keyword

nonn

Author

Robert G. Wilson v, Jun 11 2004

Extensions

2 more terms from Ryan Propper, Jan 05 2007

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007

Status

approved