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 A140869 Triangle read by rows where T(m,n) = floor((2mn+m+n-2)/2), m >= n >= 1. 3
 1, 2, 5, 4, 7, 11, 5, 10, 14, 19, 7, 12, 18, 23, 29, 8, 15, 21, 28, 34, 41, 10, 17, 25, 32, 40, 47, 55, 11, 20, 28, 37, 45, 54, 62, 71, 13, 22, 32, 41, 51, 60, 70, 79, 89, 14, 25, 35, 46, 56, 67, 77, 88, 98, 109, 16, 27, 39, 50, 62, 73, 85, 96, 108, 119, 131, 17, 30, 42, 55, 67, 80, 92, 105, 117, 130, 142, 155 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Conjecture: If h does not belong to the sequence, then 4*h+5 is prime. - Vincenzo Librandi, Nov 18 2012 First column: A001651; second column: A047215; third column: A047345. - Vincenzo Librandi, Nov 18 2012 LINKS Vincenzo Librandi, Rows n = 1..100, flattened EXAMPLE Triangle begins: 1; 2,  5; 4,  7,  11; 5,  10, 14, 19; 7,  12, 18, 23, 29; 8,  15, 21, 28, 34, 41; 10, 17, 25, 32, 40, 47, 55; etc. MATHEMATICA Flatten[Table[Floor[(2*n*m+m+n-2)/2], {n, 1, 10}, {m, n}]] (* Vladimir Joseph Stephan Orlovsky, Feb 03 2012 *) PROG (MAGMA) [Floor(((2*n*k+n+k-2)/2)): k in [1..n], n in [1..11]]; // Vincenzo Librandi, Nov 18 2012 CROSSREFS Cf. A002327, A153085, A001651, A047215, A047345. Sequence in context: A036237 A015948 A119733 * A111570 A057954 A155896 Adjacent sequences:  A140866 A140867 A140868 * A140870 A140871 A140872 KEYWORD nonn,tabl,easy AUTHOR Vincenzo Librandi, Jan 16 2009 STATUS approved

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Last modified April 17 09:29 EDT 2021. Contains 343064 sequences. (Running on oeis4.)