A280780
Numerators of coefficients in asymptotic expansion of S_n (number of simple permutations, A111111).
Original entry on oeis.org
1, -4, 2, -40, -182, -7624, -202652, -14115088, -30800534, -16435427656, -1051314228316, -22675483971248, -6980651581556876, -283099764343781072, -163910651754113166328, -43009695328217994139936, -793529010007812171331166, -20144221762701827321778088, -274475989492312981198559876
Offset: 0
Coefficients are 1, -4, 2, -40/3, -182/3, -7624/15, -202652/45, -14115088/315, -30800534/63, -16435427656/2835, ...
-
seq(N) = {
my(f = serreverse(x*Ser(vector(N, n, n!))));
Vec(x* f'/f * exp(2 + (f-x)/(x*f)));
};
apply(numerator, seq(20)) \\ Gheorghe Coserea, Jan 22 2017
A280781
Denominators of coefficients in asymptotic expansion of S_n (number of simple permutations, A111111).
Original entry on oeis.org
1, 1, 1, 3, 3, 15, 45, 315, 63, 2835, 14175, 22275, 467775, 1216215, 42567525, 638512875, 638512875, 834978375, 558242685, 1856156927625, 713906510625, 17717861581875, 2143861251406875, 9861761756471625, 147926426347074375, 75472666503609375, 48076088562799171875
Offset: 0
Coefficients are 1, -4, 2, -40/3, -182/3, -7624/15, -202652/45, -14115088/315, -30800534/63, -16435427656/2835, ...
-
seq(N) = {
my(f = serreverse(x*Ser(vector(N, n, n!))));
Vec(x* f'/f * exp(2 + (f-x)/(x*f)));
};
apply(denominator, seq(28)) \\ Gheorghe Coserea, Jan 22 2017
A280777
Denominators of coefficients in asymptotic expansion of C_n (number of connected chord diagrams, A000699).
Original entry on oeis.org
1, 2, 8, 16, 128, 1280, 3072, 215040, 3440640, 2293760, 137625600, 201850880, 72666316800, 1889324236800, 52901078630400, 176336928768000, 135426761293824, 191854578499584000, 1593868805996544000, 787371190162292736000, 31494847606491709440000, 29395191099392262144000
Offset: 0
Coefficients are 1, -5/2, -43/8, -579/16, -44477/128, -5326191/1280, -180306541/3072, ...
-
A000699_seq(N) = {
my(a = vector(N)); a[1] = 1;
for (n=2, N, a[n] = sum(k=1, n-1, (2*k-1)*a[k]*a[n-k])); a;
};
seq(N) = my(C = 'x*Ser(A000699_seq(N))); Vec(x*exp(1-(2*C+C^2)/(2*x))/C);
apply(denominator, seq(22)) \\ Gheorghe Coserea, Jan 22 2017
A280778
Numerators of coefficients in asymptotic expansion of M_n (number of monolithic chord diagrams, A280775).
Original entry on oeis.org
1, -4, -6, -154, -1610, -34588, -4666292, -553625626, -1158735422, -388434091184, -31268175015478, -2796356409576766, -4624948938397276052, -1691272281281652408568, -2154089954877183990112, -170222948041126582837968646, -5761785676811885455064909606, -55629298859254851627617870836
Offset: 0
Coefficients are 1, -4, -6, -154/3, -1610/3, -34588/5, -4666292/45, -553625626/315, -1158735422/35, ...
-
A000699_seq(N) = {
my(a = vector(N)); a[1] = 1;
for (n=2, N, a[n] = sum(k=1, n-1, (2*k-1)*a[k]*a[n-k])); a;
};
seq(N) = {
my(M = subst(x*Ser(A000699_seq(N)), x, x/(1-x)^2));
Vec(x/(1-x)*exp(1-x/2-(1-x)^2/(2*x)*(2*M + M^2))/M);
};
apply(numerator, seq(18)) \\ Gheorghe Coserea, Jan 22 2017
A280779
Denominators of coefficients in asymptotic expansion of M_n (number of monolithic chord diagrams, A280775).
Original entry on oeis.org
1, 1, 1, 3, 3, 5, 45, 315, 35, 567, 2025, 7425, 467775, 6081075, 257985, 638512875, 638512875, 172297125, 13956067125, 74246277105, 3093594879375, 14992036723125, 2143861251406875, 16436269594119375, 4226469324202125, 48028060502296875, 593531957565421875, 56437147443285984375
Offset: 0
Coefficients are 1, -4,-6, -154/3, -1610/3, -34588/5, -4666292/45, -553625626/315, -1158735422/35, ...
-
A000699_seq(N) = {
my(a = vector(N)); a[1] = 1;
for (n=2, N, a[n] = sum(k=1, n-1, (2*k-1)*a[k]*a[n-k])); a;
};
seq(N) = {
my(M = subst(x*Ser(A000699_seq(N)), x, x/(1-x)^2));
Vec(x/(1-x)*exp(1-x/2-(1-x)^2/(2*x)*(2*M + M^2))/M);
};
apply(numerator, seq(18)) \\ Gheorghe Coserea, Jan 22 2017
A280776
Numerators of coefficients in asymptotic expansion of C_n (number of connected chord diagrams, A000699).
Original entry on oeis.org
1, -5, -43, -579, -44477, -5326191, -180306541, -203331297947, -58726239094693, -781618285277957, -1025587838964854273, -35763822710356866613, -330773478104531041960421, -237504847171108896327033959, -196526060612842999084524774697, -20633624138373135772483762873819
Offset: 0
Coefficients are 1, -5/2, -43/8, -579/16, -44477/128, -5326191/1280, -180306541/3072, ...
-
A000699_seq(N) = {
my(a = vector(N)); a[1] = 1;
for (n=2, N, a[n] = sum(k=1, n-1, (2*k-1)*a[k]*a[n-k])); a;
};
seq(N) = my(C = 'x*Ser(A000699_seq(N))); Vec(x*exp(1-(2*C+C^2)/(2*x))/C);
apply(numerator, seq(16)) \\ Gheorghe Coserea, Jan 22 2017
A244522
Number of simple involutions of length n.
Original entry on oeis.org
1, 1, 2, 0, 0, 2, 4, 10, 36, 126, 454, 1744, 6892, 28486, 120962, 531660, 2398248, 11127674, 52888998, 257570104, 1282439216
Offset: 0
The a(7) = 10 simple involutions are:
01: [ 5 1 4 6 2 0 3 ] (0, 5) (1) (2, 4) (3, 6)
02: [ 4 1 6 3 0 5 2 ] (0, 4) (1) (2, 6) (3) (5)
03: [ 4 6 2 5 0 3 1 ] (0, 4) (1, 6) (2) (3, 5)
04: [ 5 3 6 1 4 0 2 ] (0, 5) (1, 3) (2, 6) (4)
05: [ 3 1 5 0 6 2 4 ] (0, 3) (1) (2, 5) (4, 6)
06: [ 3 5 2 0 6 1 4 ] (0, 3) (1, 5) (2) (4, 6)
07: [ 3 6 4 0 2 5 1 ] (0, 3) (1, 6) (2, 4) (5)
08: [ 2 5 0 3 6 1 4 ] (0, 2) (1, 5) (3) (4, 6)
09: [ 2 5 0 6 4 1 3 ] (0, 2) (1, 5) (3, 6) (4)
10: [ 2 4 0 6 1 5 3 ] (0, 2) (1, 4) (3, 6) (5)
A359856
Number of permutations of [1..n] which are indecomposable by direct and skew sums.
Original entry on oeis.org
1, 1, 0, 0, 2, 22, 202, 1854, 17866, 183806, 2029850, 24081006, 306486314, 4175102110, 60708557626, 939518187726, 15430666746826, 268214861561726, 4921023843969242, 95066628485598126, 1929291834938927210, 41042364285004263262, 913409469123533445754, 21227246586149632119438
Offset: 0
The only permutations of [1..4] which are indecomposable by direct and skew sums are 2413 and 3142.
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nmax = 20; CoefficientList[Series[2*(2 - 1/Sum[k!*x^k, {k, 0, nmax}]) - Sum[k!*x^k, {k, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 19 2023 *)
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seq(n)={my(p=sum(k=0, n, k!*x^k, O(x*x^n))); Vec(2*(2 - 1/p) - p)} \\ Andrew Howroyd, Jan 16 2023
A133262
Number of two-dimensional simple permutations.
Original entry on oeis.org
1, 4, 8, 172, 5204, 222716, 12509188, 889421564, 78097622276, 8312906703868, 1056520142488580, 158263730949406716, 27626236450406776836, 5563092167972597137404, 1280742543230231763615748, 334405228960123174787678204, 98317121153947856929753989124, 32339023133437156084762282819580, 11831483864832785151824395066146820, 4789379698138059405310741712024371196
Offset: 1
Hao Zhang and Daniel Gildea (zhanghao(AT)cs.rochester.edu), Oct 15 2007
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Feb 10 2008
A198434
Number of simple symmetric permutations of degree 2n (or 2n+1).
Original entry on oeis.org
2, 10, 90, 966, 12338, 181470, 3018082, 55995486, 1146939010, 25716746430, 626755197698, 16502357651966, 466944932413442, 14133259249586174, 455715081098876418, 15596665064842012158, 564724372634695925762, 21568978799171323200510, 866674159679235417061378, 36548294282449538711357438
Offset: 2
The simple symmetric permutations of lowest degree are 2413, 3142, 25314, 41325.
Showing 1-10 of 11 results.
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