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 A328916 Number of n-digit decimal numbers containing 123 as a substring. 1
 0, 0, 0, 1, 19, 280, 3699, 45971, 549430, 6390601, 72860039, 818050960, 9074118999, 99668329951, 1085865248550, 11749578366501, 126396115335059, 1352875288102040, 14417003302653899, 153043636911203931, 1619083493823937270, 17076417934936718801 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS See A322628 for the number of n-digit decimal numbers containing 12 as a substring. LINKS Michael Gutierrez, Table of n, a(n) for n = 0..997 FORMULA a(n) = 10*a(n-1) + 9*10^(n-4) - a(n-3). EXAMPLE For n=6, there are a(6)=3699 six-digit numbers that contain 123 as a substring. PROG (Python) a = [0, 0, 0, 1] for i in range(0, 18): a.append(10 * a[len(a) - 1] + 9 * 10 ** (len(a) - 4) - a[len(a) - 3]) print(a) CROSSREFS Cf. A322628. Sequence in context: A197742 A322628 A322053 * A081045 A155017 A199245 Adjacent sequences: A328913 A328914 A328915 * A328917 A328918 A328919 KEYWORD nonn,base,easy,changed AUTHOR Michael Gutierrez, Oct 30 2019 STATUS approved

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Last modified March 28 21:15 EDT 2023. Contains 361596 sequences. (Running on oeis4.)