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 A350731 Triangle read by rows: T(n,k) is the number of strongly connected oriented graphs on n labeled nodes with k arcs, n >= 1, k=0..n*(n-1)/2. 5
 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 6, 36, 24, 0, 0, 0, 0, 0, 24, 480, 1940, 2970, 2040, 544, 0, 0, 0, 0, 0, 0, 120, 5040, 51330, 221910, 527940, 772080, 722250, 426420, 146160, 22320, 0, 0, 0, 0, 0, 0, 0, 720, 52920, 1026060, 8810970, 43268442, 138984510 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,7 LINKS Andrew Howroyd, Table of n, a(n) for n = 1..1350 (rows 1..20) EXAMPLE Triangle begins: [1] 1; [2] 0, 0; [3] 0, 0, 0, 2; [4] 0, 0, 0, 0, 6, 36, 24; [5] 0, 0, 0, 0, 0, 24, 480, 1940, 2970, 2040, 544; ... PROG (PARI) OrientedGgf(n, y=1) = {sum(k=0, n, ((1+2*y)/(1+y))^(k*(k-1)/2)*x^k/k!, O(x*x^n) )} StrongO(n, y=1) = {my(g=serconvol(1/OrientedGgf(n, y), sum(k=0, n, x^k*(1+y)^(k*(k-1)/2), O(x*x^n)))); Vec(serlaplace(-log(g)))} row(n)={Vecrev(StrongO(n, 'y)[n], n*(n-1)/2+1)} { for(n=1, 6, print(row(n))) } CROSSREFS Row sums are A350730. The unlabeled version is A350750. Cf. A057273 (digraphs), A350732 (weakly connected). Sequence in context: A011992 A318329 A107503 * A184366 A230614 A230730 Adjacent sequences: A350728 A350729 A350730 * A350732 A350733 A350734 KEYWORD nonn,tabf AUTHOR Andrew Howroyd, Jan 11 2022 STATUS approved

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Last modified February 8 09:39 EST 2023. Contains 360138 sequences. (Running on oeis4.)