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 A132133 Number of n-digit "Punctual Birds" (cf. A131881). 6
 1, 9, 45, 270, 2104, 16941, 142245, 1226146 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The number of n-digit "Early Birds" is 9*10^(n-1) - A132133(n), which is 0, 45, 630, 6896, 73059, 757755, 7773854, ... for n = 1, 2, ... Here a(0) = 1 corresponds to the number 0 which is punctual in the sense that it does not occur before position 0, and which may be considered to have 0 digits for convenience: The index of 10^n in A131881 is then Sum_{k=0..n} a(k). - M. F. Hasler, Oct 25 2019 LINKS EXAMPLE a(2) = 45 because there are 45 2-digit Punctual Birds (10, 11, 13-20, 22, 24-30, 33, 35-40, 44, 46-50, 55, 57-60, 66, 68-70, 77, 79, 80, 88 and 90) CROSSREFS Cf. A033307, A117804, A116700, A131881, A132131, A132132. Sequence in context: A316108 A026092 A054628 * A009410 A290358 A030113 Adjacent sequences:  A132130 A132131 A132132 * A132134 A132135 A132136 KEYWORD base,nonn,more AUTHOR Graeme McRae, Aug 11 2007 EXTENSIONS Extended to a(0) = 1 by M. F. Hasler, Oct 25 2019 STATUS approved

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Last modified June 1 09:27 EDT 2020. Contains 334759 sequences. (Running on oeis4.)