A110395 a(1) = 1. a(n) = n times (10's complement of a(n-1)).

1, 18, 246, 3016, 34920, 390480, 4266640, 45866880, 487198080, 5128019200, 53591788800, 556898534400, 5760319052800, 59355533260800, 609667001088000, 6245327982592000, 63829424295936000, 651070362673152000, 6629663109210112000, 67406737815797760000

Offset

1,2

Comments

a(1)=1; a(n)=n*[10...0 - a(n-1)] for n>1 (00...0 and a[n-1] have the same number of digits). - Emeric Deutsch, Jul 31 2005

Links

Sidney Cadot, Table of n, a(n) for n = 1..200

Example

a(4) = 4* 10's complement of a(3) = 4*(1000-246) = 3016.

Maple

s:=proc(m) nops(convert(m, base, 10)) end: a[1]:=1: for n from 2 to 21 do a[n]:=n*(10^s(a[n-1])-a[n-1]) od: seq(a[n], n=1..21); # Emeric Deutsch, Jul 31 2005
# second Maple program:
a:= proc(n) option remember; `if`(n<2, n,
       n*(p-> 10^length(p)-p)(a(n-1)))
    end:
seq(a(n), n=1..25);  # Alois P. Heinz, Sep 22 2015

Mathematica

a110395[numTerms_] := Block[{complement, a},
   complement[n_] := 10^IntegerLength[n] - n;
   a[n_] := a[n] = If[n == 1, 1, n*complement[a[n - 1]]];
   Table[a[n], {n, 1, numTerms}
]]; (* Sidney Cadot, Sep 22 2015 *)
a110395[50]

Crossrefs

Cf. A110394.

Sequence in context: A016294 A153593 A001713 * A153600 A016183 A016239

Adjacent sequences: A110392 A110393 A110394 * A110396 A110397 A110398

Keyword

base,easy,nonn

Author

Amarnath Murthy, Jul 29 2005

Extensions

More terms from Emeric Deutsch, Jul 31 2005

Incorrect formula and corresponding Mathematica program removed by Sidney Cadot, Sep 22 2015

Status

approved