A067121 a(n) = floor[X/Y] where X = the concatenation of the first n even numbers in increasing order and Y = their sum.
1, 4, 20, 123, 8227, 587643, 44073235, 3427918353, 274233468240, 22437283765107, 1869773647092288, 158211616292424373, 13560995682207803419, 1175286292458009629726, 102837550590075842601095
Offset: 1
Examples
a(4): floor[2468/(2+4+6+8)] = floor[123.4] = 123.
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..352
Programs
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Maple
for i from 1 to 33 do n := 2*i:s := n:c := n:n := n-2:while(n>0) do s := s+n:g := floor(log(c+1)/log(10)):c := c+10^(g+1)*n:n := n-2:end do:a[i] := floor(c/s):end do:q := seq(a[j],j=1..33);
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Mathematica
Module[{nn=20,ev},ev=2*Range[nn];Table[Floor[FromDigits[Flatten[ IntegerDigits/@ Take[ev,n]]]/(n^2+n)],{n,nn}]] (* Harvey P. Dale, Dec 05 2014 *)
Extensions
More terms from Sascha Kurz, Mar 23 2002