The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A143037 Triangle read by rows, A000012 * A127773 * A000012. A000012 = an infinite lower triangular matrix with all 1's, A127773 = (1; 0,3; 0,0,6; 0,0,0,10;...). 3
 1, 3, 4, 6, 9, 10, 10, 16, 19, 20, 15, 25, 31, 34, 35, 21, 36, 46, 52, 55, 56, 28, 49, 64, 74, 80, 83, 84, 36, 64, 85, 100, 110, 116, 119, 120, 45, 81, 109, 130, 145, 155, 161, 164, 165, 55, 100, 136, 164, 185, 200, 210, 216, 219, 220 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Right border = tetrahedral numbers, left border = triangular numbers. Alternatively this is the square array  A(n,k)    1,   3,   6,  10,  15,  21,  28,  36,  45,  55,..    4,   9,  16,  25,  36,  49,  64,  81, 100, 121,..   10,  19,  31,  46,  64,  85, 109, 136, 166, 199,..   20,  34,  52,  74, 100, 130, 164, 202, 244, 290,..   35,  55,  80, 110, 145, 185, 230, 280, 335, 395,..   56,  83, 116, 155, 200, 251, 308, 371, 440, 515,.. read by antidiagonals where A(n,k) = n*(n^2+3*k*n+3*k^2-1)/6 is the sum of n triangular numbers starting at A000217(k). - R. J. Mathar, May 06 2015 LINKS EXAMPLE First few rows of the triangle are: 1; 3, 4; 6, 9, 10; 10, 16, 19, 20; 15, 25, 31, 34, 35; 21, 36, 46, 52, 55, 56; 28, 49, 64, 74, 80, 83, 84; 36, 64, 85, 100, 110, 116, 119, 120; ... CROSSREFS Cf. A001296 (row sums). Sequence in context: A028987 A284615 A186709 * A225059 A190899 A173671 Adjacent sequences:  A143034 A143035 A143036 * A143038 A143039 A143040 KEYWORD nonn,tabl,easy AUTHOR Gary W. Adamson & Roger L. Bagula, Jul 18 2008 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 21 10:09 EDT 2021. Contains 345360 sequences. (Running on oeis4.)