A081539 Triangle read by rows in which the n-th row contains the n numbers in increasing order formed by the concatenation of first n-1 numbers. (The digits of the numbers with 2 or more digits are taken as one entity.) First row is taken to be 0.

0, 1, 2, 12, 13, 23, 123, 124, 134, 234, 1234, 1235, 1245, 1345, 2345, 12345, 12346, 12356, 12456, 13456, 23456, 123456, 123457, 123467, 123567, 124567, 134567, 234567, 1234567, 1234568, 1234578, 1234678, 1235678, 1245678, 1345678, 2345678

Offset

1,3

Links

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

Example

0; 1,2; 12,13,23; 123,124,134,234; 1234,1235,1245,1345,2345; 12345,12346, ...

Maple

conca := proc(S) local resul, d, i ; resul := 0 ; for i from 1 to nops(S) do d := ilog10(op(i, S))+1 ; resul := resul*10^d+op(i, S) ; od ; resul ; end: A081539 := proc(row) local a, p, i; if row =1 then RETURN([0]) ; fi ; a := [] ; p := [seq(i, i=1..row)] ; for i from 1 to row do a := [op(a), conca(subsop(i=NULL, p))] ; od: sort(a)[1..row] ; end: for n from 1 to 10 do op(A081539(n)) ; od ; # R. J. Mathar, Jul 15 2007

Crossrefs

Cf. A081540.

Sequence in context: A143795 A032931 A072483 * A141273 A010097 A103761

Adjacent sequences: A081536 A081537 A081538 * A081540 A081541 A081542

Keyword

nonn,base,tabl

Author

Amarnath Murthy, Mar 29 2003

Extensions

More terms from R. J. Mathar, Jul 15 2007

Edited by Charles R Greathouse IV, Apr 30 2010

Status

approved