A133486 a(n) = Sum_{ k = 0 to n-1} ( subtract k modulo 9 from 9, multiply this by k-th power of 10 ).

9, 89, 789, 6789, 56789, 456789, 3456789, 23456789, 123456789, 9123456789, 89123456789, 789123456789, 6789123456789, 56789123456789, 456789123456789, 3456789123456789, 23456789123456789, 123456789123456789, 9123456789123456789, 89123456789123456789

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = sum(0 to n-1, ((9-(k % 9))*10^k) ).

Example

a(6) = 9+80+700+6000+50000+400000 = 456789.

Mathematica

Accumulate[Table[(9-Mod[n, 9])10^n, {n, 0, 20}]] (* or *) Table[FromDigits[PadLeft[ {}, n, Range[9]]], {n, 20}] (* Harvey P. Dale, May 08 2022 *)

Prog

(PARI) a(n) = sum(k=0, n-1, ((9-(k % 9))*10^k) ); \\ Michel Marcus, Aug 12 2013

Crossrefs

Sequence in context: A217321 A111918 A064616 * A224760 A198967 A320093

Adjacent sequences: A133483 A133484 A133485 * A133487 A133488 A133489

Keyword

nonn

Author

Prashant Garg (prashant.garg1988(AT)yahoo.com), Nov 30 2007

Extensions

More terms from Michel Marcus, Aug 12 2013

Status

approved