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A062273 a(n) is an n-digit number with digits in increasing order with 0 following 9 and this is maintained in the concatenation of any number of consecutive terms. 7
1, 23, 456, 7890, 12345, 678901, 2345678, 90123456, 789012345, 6789012345, 67890123456, 789012345678, 9012345678901, 23456789012345, 678901234567890, 1234567890123456, 78901234567890123, 456789012345678901 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is congruent to A000217(n), mod 10; i.e., the last digit of a(n) is the same as the last digit of the n-th triangular number, base 10. - Carl R. White, Oct 21 2009

LINKS

Robert Israel, Table of n, a(n) for n = 1..999

FORMULA

From Carl R. White, Oct 21 2009: (Start)

a(n) = floor( 10^[10*ceiling(n/10)+(n*[n+1]/2 mod 10)] * 1234567890/9999999999 ) mod 10^n.

The generalized form g, for any integer base b (>2), is: g(b,n) = floor( b^[b*ceiling(n/b)+(n*[n+1]/2 mod b)] * floor[ b^(b+1)/(b-1)^2 - (b+1) ] / [b^b-1]) mod b^n, so here a(n)=g(10,n). (End)

a(n) = Sum_{i=1..n} (n*(n-1)/2+i mod 10)*10^(n-i). - Vedran Glisic, Apr 08 2011

EXAMPLE

a(5) = 12345 as a(4) is 7890.

MAPLE

f:= proc(n) option remember: local d, t, k;

  d:= procname(n-1) mod 10;

  t:= 0:

  for k from 1 to n do

    d:= d+1 mod 10;

    t:= t + d*10^(n-k)

  od:

t

end proc:

f(1):= 1:

map(f, [$1..30]); # Robert Israel, Apr 02 2018

MATHEMATICA

FromDigits/@Table[Take[PadRight[{}, 250, Join[Range[9], {0}]], {(n(n+1))/2+ 1, ((n+1)(n+2))/2}], {n, 0, 20}] (* Harvey P. Dale, May 15 2015 *)

CROSSREFS

Sequence in context: A174262 A174425 A076068 * A066547 A001369 A007923

Adjacent sequences:  A062270 A062271 A062272 * A062274 A062275 A062276

KEYWORD

nonn,base,easy

AUTHOR

Amarnath Murthy, Jun 17 2001

EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), Jun 18 2001

STATUS

approved

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Last modified September 19 11:33 EDT 2021. Contains 347556 sequences. (Running on oeis4.)