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 A334691 Irregular triangle read by rows: T(n,k) (n >= 1, 2 <= k <= 2*n) = number of interior vertices in the n-th figure shown in A255011 (meaning the figure with 4n points on the perimeter) where k lines meet. 6
 1, 20, 8, 1, 204, 32, 8, 0, 1, 616, 152, 20, 8, 4, 0, 1, 2428, 252, 36, 16, 4, 0, 0, 0, 1, 3968, 572, 156, 72, 16, 8, 4, 0, 4, 0, 1, 11164, 900, 120, 52, 16, 8, 4, 0, 0, 0, 0, 0, 1, 16884, 1712, 396, 132, 40, 20, 8, 8, 8, 0, 0, 0, 0, 0, 1, 30116, 2536, 600, 140, 60, 24, 8, 20, 8, 0, 0, 0, 0, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS No formula is known. LINKS Table of n, a(n) for n=1..81. Scott R. Shannon, Data for triangles A334691 and A334699 Scott R. Shannon, Colored illustration for n = 2 Scott R. Shannon, Illustration for n=3 showing interior vertices color-coded according to multiplicity. EXAMPLE Triangle begins: 1; 20,8,1; 204,32,8,0,1; 616,152,20,8,4,0,1; 2428,252,36,16,4,0,0,0,1; 3968,572,156,72,16,8,4,0,4,0,1; 11164,900,120,52,16,8,4,0,0,0,0,0,1; 16884,1712,396,132,40,20,8,8,8,0,0,0,0,0,1; 30116,2536,600,140,60,24,8,20,8,0,0,0,0,0,0,0,1; 43988,4056,948,312,84,56,52,20,,8,0,0,4,0,0,0,0,0,1; 82016,4660,580,228,48,84,4,4,4,8,4,0,0,0,0,0,0,0,0,0,1; 90088,8504,1840,780,424,128,68,32,32,0,0,8,24,0,0,0,4,0,0,0,0,0,1; 168360,8284,1056,396,128,100,52,12,4,4,4,8,4,0,0,0,0,0,0,0,0,0,0,0,1; 202332,13144,2980,924,256,144,140,60,44,4,0,8,8,8,0,0,4,0,0,0,0,0,0,0,0,0,1; ... CROSSREFS Cf. A255011, A331449, A334690 (row sums), A334692 (column k=2), A334693 (k=3), A334694-A334699. Sequence in context: A196102 A196099 A102409 * A097395 A108967 A097390 Adjacent sequences: A334688 A334689 A334690 * A334692 A334693 A334694 KEYWORD nonn,tabf AUTHOR Scott R. Shannon and N. J. A. Sloane, May 18 2020 STATUS approved

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Last modified July 15 12:56 EDT 2024. Contains 374332 sequences. (Running on oeis4.)