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A322071
Triangle read by rows: T(n, k) is the largest integer m such that m*k^k <= 2*n^k.
1
2, 4, 2, 6, 4, 2, 8, 8, 4, 2, 10, 12, 9, 4, 2, 12, 18, 16, 10, 4, 2, 14, 24, 25, 18, 10, 5, 2, 16, 32, 37, 32, 20, 11, 5, 2, 18, 40, 54, 51, 37, 22, 11, 5, 2, 20, 50, 74, 78, 64, 42, 24, 11, 5, 2, 22, 60, 98, 114, 103, 75, 47, 25, 12, 5, 2, 24, 72, 128, 162, 159, 128, 87, 51, 26, 12, 5, 2
OFFSET
1,1
COMMENTS
For k >= 5 and n >= k, T(n, k) is the maximum number of induced copies of a cycle of length k in a n-vertex graph (see Král, Norin and Volec Theorem 1).
LINKS
Daniel Král, Sergey Norin and Jan Volec, A bound on the inducibility of cycles, arXiv:1801.01556 [math.CO], 2018; Journal of Combinatorial Theory, Series A, 161 (2019) 359-363.
FORMULA
T(n, k) = floor(2*n^k/k^k).
T(n, k) = floor(A005843(n^k/A000312(k))).
EXAMPLE
n\k| 1 2 3 4 5 6 7 8 9 10
---+----------------------------------------
1 | 2
2 | 4 2
3 | 6 4 2
4 | 8 8 4 2
5 | 10 12 9 4 2
6 | 12 18 16 10 4 2
7 | 14 24 25 18 10 5 2
8 | 16 32 37 32 20 11 5 2
9 | 18 40 54 51 37 22 11 5 2
10 | 20 50 74 78 64 42 24 11 5 2
...
MAPLE
a := (n, k) -> floor(2*n^k/k^k): seq(seq(a(n, k), k = 1 .. n), n = 1 .. 20)
MATHEMATICA
Flatten[Table[Floor[2*n^k/k^k], {n, 1, 15}, {k, 1, n}]]
PROG
(Magma) [[Floor(2*n^k/k^k): k in [1..n]]: n in [1..10]]; // triangle output
(Maxima) sjoin(v, j) := apply(sconcat, rest(join(makelist(j, length(v)), v)))$ display_triangle(n) := for i from 1 thru n do disp(sjoin(makelist(floor(2*i^j/j^j), j, 1, i), " ")); display_triangle(10);
(PARI)
T(n, k) = floor(2*n^k/k^k);
tabl(nn) = for(i=1, nn, for(j=1, i, print1(T(i, j), ", ")); print);
tabl(10) \\ triangle output
(GAP) Flat(List([1..15], n->List([1..n], k->Int(2*n^k/k^k)))); # Muniru A Asiru, Nov 25 2018
CROSSREFS
Cf. A000312, A005843, A322072 (row sums).
Sequence in context: A215841 A272327 A212012 * A176342 A374456 A340148
KEYWORD
nonn,tabl
AUTHOR
Stefano Spezia, Nov 25 2018
EXTENSIONS
a(71)-a(78) from Muniru A Asiru, Nov 25 2018
STATUS
approved