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 A109161 Triangle read by rows: T(n, k) = n*(n+9) + k + 5, with T(0, 0) = 5 and T(1, 0) = 15. 3
 5, 15, 16, 27, 28, 29, 41, 42, 43, 44, 57, 58, 59, 60, 61, 75, 76, 77, 78, 79, 80, 95, 96, 97, 98, 99, 100, 101, 117, 118, 119, 120, 121, 122, 123, 124, 141, 142, 143, 144, 145, 146, 147, 148, 149, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS G. C. Greubel, Rows n=0..100 of the triangle, flattened S. Helgason, A Centennial: Wilhelm Killing and the Exceptional Groups, Mathematical Intelligencer 12, no. 3 (1990). [See p. 3.] FORMULA T(n, k) = n*(n+9) + k + 5, with T(0, 0) = 5 and T(1, 0) = 15. EXAMPLE Triangle begins as: 5; 15, 16; 27, 28, 29; 41, 42, 43, 44; 57, 58, 59, 60, 61; 75, 76, 77, 78, 79, 80; MATHEMATICA T[n_, k_]:= If[n==0 && k==0, 5, If[k==0 && n==1, 15, n*(n+9) +k +5]]; Table[T[n, k], {n, 0, 12}, {k, 0, n}]//Flatten PROG (Sage) @CachedFunction def T(n, k): if (n==0 and k==0): return 5 elif (k==0 and n==1): return 15 else: return n*(n + 9) + k + 5 flatten([[T(n, k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Feb 05 2021 CROSSREFS Cf. A106373, A106374, A106403. Sequence in context: A102185 A030486 A101238 * A065908 A297124 A166503 Adjacent sequences: A109158 A109159 A109160 * A109162 A109163 A109164 KEYWORD nonn,tabl,easy,less AUTHOR Roger L. Bagula, May 06 2007 EXTENSIONS More terms and edits by G. C. Greubel, Feb 05 2021 STATUS approved

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Last modified December 3 11:24 EST 2022. Contains 358517 sequences. (Running on oeis4.)