|
| |
|
|
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.
|
|
6
| |
|
|
1, 23, 456, 7890, 12345, 678901, 2345678, 90123456, 789012345, 6789012345, 67890123456, 789012345678, 9012345678901, 23456789012345, 678901234567890, 1234567890123456, 78901234567890123, 456789012345678901
(list; graph; refs; listen; history; 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 [From Carl R. White (oeisfan(AT)phodd.net), Oct 21 2009]
|
|
|
FORMULA
| Contribution from Carl R. White (oeisfan(AT)phodd.net), Oct 21 2009: (Start)
a(n) = floor( 10^[10*ceiling(n/10)+(n*[n+1]/2 mod 10)] * 1234567890/9999999999 ) mod 10^n
The generalised 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.
|
|
|
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 (amarnath_murthy(AT)yahoo.com), Jun 17 2001
|
|
|
EXTENSIONS
| More terms from Larry Reeves (larryr(AT)acm.org), Jun 18 2001
|
| |
|
|
