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 A130487 a(n) = Sum_{k=0..n} (k mod 9) (Partial sums of A010878). 11
 0, 1, 3, 6, 10, 15, 21, 28, 36, 36, 37, 39, 42, 46, 51, 57, 64, 72, 72, 73, 75, 78, 82, 87, 93, 100, 108, 108, 109, 111, 114, 118, 123, 129, 136, 144, 144, 145, 147, 150, 154, 159, 165, 172, 180, 180, 181, 183, 186, 190, 195, 201, 208, 216, 216, 217, 219, 222, 226 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Let A be the Hessenberg n X n matrix defined by A[1,j]=j mod 9, A[i,i]:=1, A[i,i-1]=-1. Then, for n >= 1, a(n)=det(A). [Milan Janjic, Jan 24 2010] LINKS Shawn A. Broyles, Table of n, a(n) for n = 0..1000 FORMULA a(n) = 36*floor(n/9) + A010878(n)*(A010878(n) + 1)/2. G.f.: (Sum_{k=1..8} k*x^k)/((1-x^9)(1-x)). G.f.: x(8x^9-9x^8+1)/((1-x^9)(1-x)^3). PROG (PARI) a(n) = sum(k=0, n, k % 9); \\ Michel Marcus, Apr 28 2018 CROSSREFS Cf. A010872, A010873, A010874, A010875, A010876, A010877, A130481, A130482, A130483, A130484, A130485, A130486. Sequence in context: A124157 A033440 A067525 * A231684 A108923 A033441 Adjacent sequences:  A130484 A130485 A130486 * A130488 A130489 A130490 KEYWORD nonn AUTHOR Hieronymus Fischer, May 31 2007 STATUS approved

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Last modified November 18 09:23 EST 2018. Contains 317279 sequences. (Running on oeis4.)