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%I A109161 #16 Feb 06 2021 08:51:57
%S A109161 5,15,16,27,28,29,41,42,43,44,57,58,59,60,61,75,76,77,78,79,80,95,96,
%T A109161 97,98,99,100,101,117,118,119,120,121,122,123,124,141,142,143,144,145,
%U A109161 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
%N A109161 Triangle read by rows: T(n, k) = n*(n+9) + k + 5, with T(0, 0) = 5 and T(1, 0) = 15.
%H A109161 G. C. Greubel, <a href="/A109161/b109161.txt">Rows n=0..100 of the triangle, flattened</a>
%H A109161 S. Helgason, <a href="https://web.archive.org/web/20060913232213/http://ocw.mit.edu/NR/rdonlyres/Mathematics/18-755Fall-2004/12BE03CD-1B28-41C6-8D2A-85097D4EEB68/0/helgacentSTD.pdf">A Centennial: Wilhelm Killing and the Exceptional Groups</a>, Mathematical Intelligencer 12, no. 3 (1990). [See p. 3.]
%F A109161 T(n, k) = n*(n+9) + k + 5, with T(0, 0) = 5 and T(1, 0) = 15.
%e A109161 Triangle begins as:
%e A109161    5;
%e A109161   15, 16;
%e A109161   27, 28, 29;
%e A109161   41, 42, 43, 44;
%e A109161   57, 58, 59, 60, 61;
%e A109161   75, 76, 77, 78, 79, 80;
%t A109161 T[n_, k_]:= If[n==0 && k==0, 5, If[k==0 && n==1, 15, n*(n+9) +k +5]];
%t A109161 Table[T[n, k], {n, 0, 12}, {k, 0, n}]//Flatten
%o A109161 (Sage)
%o A109161 @CachedFunction
%o A109161 def T(n, k):
%o A109161     if (n==0 and k==0): return 5
%o A109161     elif (k==0 and n==1): return 15
%o A109161     else: return n*(n + 9) + k + 5
%o A109161 flatten([[T(n,k) for k in (0..n)] for n in (0..12)]) # _G. C. Greubel_, Feb 05 2021
%Y A109161 Cf. A106373, A106374, A106403.
%K A109161 nonn,tabl,easy,less
%O A109161 1,1
%A A109161 _Roger L. Bagula_, May 06 2007
%E A109161 More terms and edits by _G. C. Greubel_, Feb 05 2021

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