A293114
Number of sets of nonempty words with a total of n letters over n-ary alphabet such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
Original entry on oeis.org
1, 1, 2, 6, 15, 45, 136, 430, 1415, 4845, 17235, 63509, 242854, 959904, 3926209, 16564083, 72097127, 322898943, 1487602607, 7034420691, 34122991199, 169499127425, 861596397518, 4475340840980, 23738200183570, 128427236055296, 708248486616539, 3977551340260517
Offset: 0
a(0) = 1: {}.
a(1) = 1: {a}.
a(2) = 2: {aa}, {ab}.
a(3) = 6: {a,aa}, {a,ab}, {aaa}, {aab}, {aba}, {abc}.
-
g:= proc(n) option remember;
`if`(n<2, 1, g(n-1)+(n-1)*g(n-2))
end:
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(b(n-i*j, i-1)*binomial(g(i), j), j=0..n/i)))
end:
a:= n-> b(n$2):
seq(a(n), n=0..35);
-
g[n_] := g[n] = If[n < 2, 1, g[n - 1] + (n - 1)*g[n - 2]];
b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[b[n - i*j, i - 1]* Binomial[g[i], j], {j, 0, n/i}]]];
a[n_] := b[n, n];
Table[a[n], {n, 0, 35}] (* Jean-François Alcover, Jun 06 2018, from Maple *)
A293128
Number of standard Young tableaux of 2n cells and height <= n.
Original entry on oeis.org
1, 1, 6, 51, 588, 7990, 126060, 2242618, 44546320, 977152266, 23500234512, 615372604033, 17442275104496, 532242021137346, 17399782340548920, 606732491690590816, 22477989291826848000, 881635273413199806994, 36493478646922003374096, 1589642562747880936613248
Offset: 0
-
h:= l-> (n-> add(i, i=l)!/mul(mul(1+l[i]-j+add(`if`(l[k]
`if`(n=0 or i=1, h([l[], 1$n]), add(
g(n-i*j, i-1, [l[], i$j]), j=0..n/i)):
a:= n-> g(2*n, n, []):
seq(a(n), n=0..15);
-
h[l_] := With[{n = Length[l]}, Total[l]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] < j, 0, 1], {k, i + 1, n}], {j, 1, l[[i]]}], {i, 1, n}]];
g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Table[1, {n}]]], Sum[g[n - i*j, i - 1, Join[l, Table[i, {j}]]], {j, 0, n/i}]];
a[n_] := g[2n, n, {}];
a /@ Range[0, 15] (* Jean-François Alcover, Jan 02 2021, after Alois P. Heinz *)
A217323
Number of self-inverse permutations in S_n with longest increasing subsequence of length 3.
Original entry on oeis.org
1, 3, 11, 31, 92, 253, 709, 1936, 5336, 14587, 40119, 110202, 304137, 840597, 2332469, 6487762, 18106906, 50667263, 142194843, 400057791, 1128408337, 3190023641, 9038202201, 25659417876, 72987714502, 207983161609, 593665226069, 1697230353691, 4859461136196
Offset: 3
a(3) = 1: 123.
a(4) = 3: 1243, 1324, 2134.
a(5) = 11: 12543, 13254, 14325, 14523, 15342, 21354, 21435, 32145, 34125, 42315, 52341.
-
a:= proc(n) option remember; `if`(n<3, 0, `if`(n=3, 1,
((n+1)*(6*n^3-5*n^2-7*n-24)*a(n-1)
+n*(n-1)*(21*n^2-28*n-109)*a(n-2)
-2*(n-1)*(n-2)*(12*n^2+11*n-3)*a(n-3)
-12*(3*n+5)*(n-1)*(n-2)*(n-3)*a(n-4))/
((n-3)*(3*n+2)*(n+2)*(n+1))))
end:
seq(a(n), n=3..40);
-
MotzkinNumber = DifferenceRoot[Function[{y, n}, {(-3n-3)*y[n] + (-2n-5)*y[n+1] + (n+4)*y[n+2] == 0, y[0] == 1, y[1] == 1}]];
a[n_] := MotzkinNumber[n] - Binomial[n, Quotient[n, 2]];
Table[a[n], {n, 3, 40}] (* Jean-François Alcover, Oct 27 2021, from 2nd formula *)
A229053
Number of standard Young tableaux of n cells and height <= 11.
Original entry on oeis.org
1, 1, 2, 4, 10, 26, 76, 232, 764, 2620, 9496, 35696, 140151, 568491, 2390311, 10347911, 46191551, 211671999, 996269310, 4801547628, 23695885170, 119481280210, 615372604033, 3232009497979, 17302866542177, 94301143232321, 522945331559246, 2947729723188352
Offset: 0
-
RecurrenceTable[{-10395 (-5+n) (-4+n) (-3+n) (-2+n) (-1+n) a[-6+n]-3 (-4+n) (-3+n) (-2+n) (-1+n) (28701+2578 n) a[-5+n]+(-3+n) (-2+n) (-1+n) (331317+74458 n+3319 n^2) a[-4+n]+2 (-2+n) (-1+n) (546120+154023 n+11843 n^2+270 n^3) a[-3+n]-(-1+n) (1857231+1090536 n+149299 n^2+7472 n^3+125 n^4) a[-2+n]+(-2755377-1658520 n-265085 n^2-17752 n^3-535 n^4-6 n^5) a[-1+n]+(10+n) (18+n) (24+n) (28+n) (30+n) a[n]==0,a[1]==1,a[2]==2,a[3]==4,a[4]==10,a[5]==26,a[6]==76}, a, {n, 20}]
A293111
Number of multisets of nonempty words with a total of 2n letters over n-ary alphabet containing the n-th letter such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
Original entry on oeis.org
1, 2, 10, 58, 439, 3767, 37481, 405672, 4816390, 60748286, 817467196, 11533898929, 170979909037, 2635984019533, 42297026556483, 701880878089205, 12045976560853148, 212911592290588547, 3874514946593004395, 72378921228197309169, 1387364840045160600103
Offset: 0
A293115
Number of sets of nonempty words with a total of 2n letters over n-ary alphabet containing the n-th letter such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
Original entry on oeis.org
1, 1, 8, 53, 410, 3576, 35878, 391136, 4666521, 59096165, 797628339, 11282268353, 167582833398, 2587994886476, 41585338511800, 690912445945576, 11870082701946292, 209995330141487944, 3824511903396303251, 71496027436457015058, 1371314535020854180410
Offset: 0
A213290
Number of n-length words w over binary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.
Original entry on oeis.org
1, 2, 4, 5, 9, 14, 27, 46, 91, 162, 323, 589, 1177, 2179, 4357, 8152, 16303, 30746, 61491, 116689, 233377, 445095, 890189, 1704795, 3409589, 6552379, 13104757, 25258601, 50517201, 97617061, 195234121, 378098956, 756197911, 1467343306, 2934686611, 5704370761
Offset: 0
a(0) = 1: the empty word.
a(1) = 2: a, b for alphabet {a,b}.
a(2) = 4: aa, ab, ba, bb.
a(3) = 5: aaa, aab, aba, baa, bbb.
a(4) = 9: aaaa, aaab, aaba, aabb, abaa, abab, baaa, baab, bbbb.
a(5) = 14: aaaaa, aaaab, aaaba, aaabb, aabaa, aabab, aabba, abaaa, abaab, ababa, baaaa, baaab, baaba, bbbbb.
-
b:= n-> `if`(n<0, 0, binomial(n, ceil(n/2))):
a:= n-> b(n) +b(n-2) +`if`(n>0, 1, 0):
seq(a(n), n=0..40);
A217321
Number of self-inverse permutations in S_n with longest increasing subsequence of length 9.
Original entry on oeis.org
1, 9, 89, 639, 4655, 30330, 198148, 1233743, 7694099, 46938514, 287070944, 1738940782, 10570927022, 64059763010, 389873574058, 2373799261605, 14522526860316, 89060416668016, 548932942208392, 3395326330414774, 21109553761623110, 131785019270029876
Offset: 9
A217322
Number of self-inverse permutations in S_n with longest increasing subsequence of length 10.
Original entry on oeis.org
1, 10, 109, 857, 6798, 48007, 338529, 2267425, 15164662, 98964444, 645978814, 4168541022, 26949303558, 173445855265, 1119737108943, 7224864497439, 46800745943134, 303692912870933, 1979556048016406, 12943419575576650, 85040314513698164, 560910092712436079
Offset: 10
A217324
Number of self-inverse permutations in S_n with longest increasing subsequence of length 4.
Original entry on oeis.org
1, 4, 19, 69, 265, 929, 3356, 11626, 41117, 142206, 499836, 1734328, 6099193, 21282265, 75125770, 263906332, 936517637, 3313246237, 11827430209, 42139231729, 151339387003, 542857007499, 1961171657524, 7079621540798, 25720257983591, 93396276789196
Offset: 4
a(4) = 1: 1234.
a(5) = 4: 12354, 12435, 13245, 21345.
a(6) = 19: 123654, 124365, 125436, 125634, 126453, 132465, 132546, 143256, 145236, 153426, 163452, 213465, 213546, 214356, 321456, 341256, 423156, 523416, 623451.
-
a:= proc(n) option remember; `if`(n<4, 0, `if`(n=4, 1,
((2+n)*(30*n^5+199*n^4-374*n^3-1537*n^2-406*n+408)*a(n-1)
-4*(n-1)*(n-2)*(120*n^4+46*n^3-471*n^2+371*n+204)*a(n-3)
+(n-1)*(285*n^5-262*n^4-2755*n^3-1520*n^2+820*n-48)*a(n-2)
-48*(n-1)*(n-3)*(3*n+7)*(5*n+4)*(n-2)^2*a(n-4))/
((n-4)*(5*n-1)*(3*n+4)*(n+4)*(n+3)*(n+2))))
end:
seq(a(n), n=4..40);
-
h[l_] := With[{n = Length[l]}, Total[l]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i + 1, n}], {j, 1, l[[i]]}], {i, 1, n}]];
g[n_, i_, l_] := g[n, i, l] = If[n == 0 || i == 1, Function[p, h[p]*x^If[p == {}, 0, p[[1]]]][Join[l, Array[1&, n]]], Sum[g[n - i*j, i - 1, Join[l, Array[i&, j]]], {j, 0, n/i}]];
a[n_] := a[n] = Coefficient[g[n, n, {}], x, 4];
Table[Print[n, " ", a[n]]; a[n], {n, 4, 40}]
(* or: *)
MotzkinNumber = DifferenceRoot[Function[{y, n}, {(-3n-3)*y[n] + (-2n-5)*y[n+1] + (n+4)*y[n+2] == 0, y[0] == 1, y[1] == 1}]];
a[n_] := CatalanNumber[Quotient[n+1, 2]]*CatalanNumber[Quotient[n+2, 2]] - MotzkinNumber[n];
Table[a[n], {n, 4, 40}]
(* Jean-François Alcover, Oct 27 2021, after Alois P. Heinz in A047884 and second formula *)
Comments