login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 24 01:41 EDT 2021. Contains 346269 sequences. (Running on oeis4.)