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A089908 Sum of digits of numbers between 0 and (7/9)*(10^n-1). 6
0, 28, 609, 9555, 130501, 1654947, 20049393, 235493839, 2704938285, 30549382731, 340493827177, 3754938271623, 41049382716069, 445493827160515, 4804938271604961, 51549382716049407, 550493827160493853 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
From a suggestion of Yalcin Aktar
LINKS
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
Sequence in context: A264459 A004371 A283096 * A038121 A240684 A184329
KEYWORD
nonn,base,easy,changed
AUTHOR
Benoit Cloitre, Nov 14 2003
STATUS
approved

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Last modified March 29 08:00 EDT 2024. Contains 371265 sequences. (Running on oeis4.)