A101563 a(n)=(-1)^n*coefficient of x^n in sum{k>=1,x^(k-1)/(1+10x^k)}.

1, 9, 101, 1009, 10001, 99909, 1000001, 10001009, 100000101, 999990009, 10000000001, 100000100909, 1000000000001, 9999999000009, 100000000010101, 1000000010001009, 10000000000000001, 99999999900099909

Offset

0,2

Links

Table of n, a(n) for n=0..17.

Formula

a(n)=sum{k=0..n, (-1)^(n-k)*if(mod(n+1, k+1)=0, 1, 0)*10^k}

Crossrefs

Cf. A051731, A081295, A048272, A101561, A101562.

Sequence in context: A360348 A174509 A103461 * A269732 A007133 A183518

Adjacent sequences: A101560 A101561 A101562 * A101564 A101565 A101566

Keyword

easy,nonn

Author

Paul Barry, Dec 07 2004

Status

approved