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 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. 4
 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 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS 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

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Last modified April 20 09:21 EDT 2021. Contains 343125 sequences. (Running on oeis4.)