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 A081551 Triangle, read by rows, in which the n-th row contains n smallest n-digit numbers. 3
 1, 10, 11, 100, 101, 102, 1000, 1001, 1002, 1003, 10000, 10001, 10002, 10003, 10004, 100000, 100001, 100002, 100003, 100004, 100005, 1000000, 1000001, 1000002, 1000003, 1000004, 1000005, 1000006, 10000000, 10000001, 10000002, 10000003, 10000004, 10000005, 10000006, 10000007 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS This sequence has asymptotic density 0 and Banach density 1 (see Mithun Kumar Das reference p.2). - Franz Vrabec, Jul 28 2019 LINKS G. C. Greubel, Rows n = 0..50 of the triangle, flattened Mithun Kumar Das, Pramod Eyyunni, and Bhuwanesh Rao Patil, Sparse subsets of the natural numbers and Euler's totient function, arXiv:1907.09847v1 [math.NT] 23 Jul 2019. FORMULA From Franz Vrabec, Jul 28 2019: (Start) T(n, k) = 10^(n-1) + k - 1. As a one-dimensional sequence: a(n) = 10^m + n - (m^2 + m + 2)/2 where m = floor((-1 + sqrt(8*n-7))/2). (End) EXAMPLE Triangle begins as: 1; 10, 11; 100, 101, 102; 1000, 1001, 1002, 1003; 10000, 10001, 10002, 10003, 10004; 100000, 100001, 100002, 100003, 100004, 100005; MATHEMATICA Table[10^(n-1) +k-1, {n, 12}, {k, n}]//Flatten (* G. C. Greubel, May 27 2021 *) PROG (Sage) flatten([[10^(n-1) +k-1 for k in (1..n)] for n in (1..12)]) # G. C. Greubel, May 27 2021 CROSSREFS Cf. A081552, A081553. Sequence in context: A332795 A303605 A266946 * A257831 A007088 A115848 Adjacent sequences: A081548 A081549 A081550 * A081552 A081553 A081554 KEYWORD base,easy,nonn,tabl AUTHOR Amarnath Murthy, Apr 01 2003 EXTENSIONS More terms from Philippe Deléham, Mar 28 2009 STATUS approved

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Last modified September 10 00:26 EDT 2024. Contains 375769 sequences. (Running on oeis4.)