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 A066686 Array T(i,j) read by antidiagonals, where T(i,j) is the concatenation of i and j (1<=i, 1<=j). 2
 11, 12, 21, 13, 22, 31, 14, 23, 32, 41, 15, 24, 33, 42, 51, 16, 25, 34, 43, 52, 61, 17, 26, 35, 44, 53, 62, 71, 18, 27, 36, 45, 54, 63, 72, 81, 19, 28, 37, 46, 55, 64, 73, 82, 91, 110, 29, 38, 47, 56, 65, 74, 83, 92, 101, 111, 210, 39, 48, 57, 66, 75, 84, 93, 102, 111 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The element at T(i,j) is the {(i+j-1)(i+j-2)/2 + i}-th element read in the sequence. LINKS Alexander Bogomolny, What is a number? Boris Putievskiy, Transformations [Of] Integer Sequences And Pairing Functions, arXiv preprint arXiv:1212.2732, 2012. EXAMPLE The array begins 11 12 13 14 15 16 17 18 19 110 ... 21 22 23 24 25 26 27 28 29 210 ... 31 32 33 34 35 36 37 38 39 310 ... 41 42 43 44 45 46 47 48 49 410 ... MATHEMATICA a = {}; Do[ a = Append[a, ToExpression[ StringJoin[ ToString[k], ToString[n - k]]]], {n, 2, 13}, {k, 1, n - 1} ]; a CROSSREFS Sequence in context: A057303 A121979 A109372 * A125887 A107478 A153146 Adjacent sequences:  A066683 A066684 A066685 * A066687 A066688 A066689 KEYWORD easy,nonn,tabl,base AUTHOR Robert G. Wilson v, Jan 11 2002 STATUS approved

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