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A081551 Triangle read by rows in which the n-th row contains n smallest n-digit numbers. 2
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

Table of n, a(n) for n=1..36.

Mithun Kumar Das, Pramod Eyyunni, Bhuwanesh Rao Patil, Sparse subsets of the natural numbers and Euler's totient function, arXiv:1907.09847v1 [math.NT] 23 Jul 2019.

FORMULA

T(n,k) = 10^(n-1)+k-1. But considered as one-dimensional sequence, a(n) = 10^m+n-(m^2+m+2)/2 where m = floor((-1+sqrt(8*n-7))/2). - Franz Vrabec, Jul 28 2019

EXAMPLE

1; 10,11; 100,101,102; 1000,1001,1002,1003; ...

CROSSREFS

Cf. A081552, A081553.

Sequence in context: A178569 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 20 02:20 EDT 2019. Contains 327207 sequences. (Running on oeis4.)