OFFSET
0,2
COMMENTS
From a suggestion of Yalcin Aktar
LINKS
Index entries for linear recurrences with constant coefficients, signature (22,-141,220,-100).
FORMULA
a(n) = s(7, n-1) where s(a, k)=a*(k+1)+a^2*sum(i=0, k, i*10^(k-i))+sum(i=0, k, 5*a*(9*(k-i)+a- 1)*10^(k-i-1)).
a(n) = (7*(-22*(-1+10^n)+9*(4+9*10^n)*n))/162. G.f.: 7*x*(15*x^2-x+4) / ((x-1)^2*(10*x-1)^2). - Colin Barker, Jun 14 2013
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Benoit Cloitre, Nov 14 2003
STATUS
approved