A374980
Number of multiset permutations of {1, 1, 2, 2, ..., n, n} with no fixed pair (j,j).
Original entry on oeis.org
1, 0, 5, 74, 2193, 101644, 6840085, 630985830, 76484389121, 11792973495032, 2254432154097861, 523368281765512930, 145044815855963403985, 47302856057098946329284, 17933275902554972391519893, 7820842217155394547769452734, 3887745712142302082441578104705
Offset: 0
a(2) = 5: 1212, 1221, 2112, 2121, 2211.
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a:= proc(n) option remember; `if`(n<3, [1, 0, 5][n+1],
(n-1)*((2*n+1)*a(n-1)+(4*n-3)*a(n-2)+2*(n-2)*a(n-3)))
end:
seq(a(n), n=0..16);
A116219
If X_1,...,X_n is a partition of a 3n-set X into 3-blocks then a(n) is equal to the number of permutations f of X such that f(X_i) <> X_i, (i=1,...,n).
Original entry on oeis.org
0, 684, 350352, 470444112, 1293433432704, 6355554535465920, 50823027472983319296, 618002474327361540442368, 10855431334634213344062394368, 264600531449039456516679858441216, 8665832467934840277899318819803484160, 371368757645100314808527266212241861300224
Offset: 1
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List([1..20], n-> Sum([0..n], j-> (-6)^j*Binomial(n,j)* Factorial(3*n-3*j))); # G. C. Greubel, May 11 2019
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[(&+[(-6)^j*Binomial(n, j)*Factorial(3*n-3*j): j in [0..n]]): n in [1..20]]; // G. C. Greubel, May 11 2019
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a:=n->sum((-6)^i*binomial(n,i)*(3*n-3*i)!,i=0..n).
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Table[Sum[(-6)^i*Binomial[n, i]*(3*n - 3*i)!, {i, 0, n}], {n, 1, 20}] (* G. C. Greubel, May 11 2019 *)
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{a(n) = sum(j=0,n, (-6)^j*binomial(n,j)*(3*(n-j))!)}; \\ G. C. Greubel, May 11 2019
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[sum((-6)^j*binomial(n,j)*factorial(3*n-3*j) for j in (0..n)) for n in (1..20)] # G. C. Greubel, May 11 2019
A116220
If X_1,...,X_n is a partition of a 4n-set X into 4-blocks then a(n) is equal to the number of permutations f of X such that f(X_i) <> X_i, (i=1,...,n).
Original entry on oeis.org
0, 39744, 476126208, 20876944084992, 2430394026897309696, 620098244484731975761920, 304784138698487640049544331264, 263072308376236973471661993731555328, 371936496850567880606221498503260339699712, 815826011669313721421241471652159968573722198016
Offset: 1
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List([1..20], n-> Sum([0..n], j-> (-24)^j*Binomial(n,j)* Factorial(4*n-4*j))); # G. C. Greubel, May 11 2019
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[(&+[(-24)^j*Binomial(n, j)*Factorial(4*n-4*j): j in [0..n]]): n in [1..20]]; // G. C. Greubel, May 11 2019
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a:=n->sum((-24)^i*binomial(n,i)*(4*n-4*i)!,i=0..n).
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Table[Sum[(-24)^j*Binomial[n, j]*(4*n-4*j)!, {j,0,n}], {n, 1, 20}] (* G. C. Greubel, May 11 2019 *)
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{a(n) = sum(j=0,n, (-24)^j*binomial(n,j)*(4*(n-j))!)}; \\ G. C. Greubel, May 11 2019
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[sum((-24)^j*binomial(n,j)*factorial(4*n-4*j) for j in (0..n)) for n in (1..20)] # G. C. Greubel, May 11 2019
A116221
If X_1,...,X_n is a partition of a 5n-set X into 5-blocks then a(n) is equal to the number of permutations f of X such that f(X_i) <> X_i, (i=1,...,n).
Original entry on oeis.org
0, 3614400, 1306371456000, 2432274637386240000, 15509750490368582860800000, 265241692266421512138485760000000, 10332925158674345473855915900600320000000, 815905363532798455769292988741440720076800000000, 119621339682330952236606797649198078512534126592000000000
Offset: 1
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List([1..20], n-> Sum([0..n], j-> (-120)^j*Binomial(n,j)* Factorial(5*n-5*j))); # G. C. Greubel, May 11 2019
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[(&+[(-120)^j*Binomial(n, j)*Factorial(5*n-5*j): j in [0..n]]): n in [1..20]]; // G. C. Greubel, May 11 2019
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a:=n->sum((-120)^i*binomial(n,i)*(5*n-5*i)!,i=0..n).
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Table[Sum[(-5!)^j*Binomial[n, j]*(5*n-5*j)!, {j,0,n}], {n,1,20}] (* G. C. Greubel, May 11 2019 *)
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{a(n) = sum(j=0,n, (-120)^j*binomial(n,j)*(5*(n-j))!)}; \\ G. C. Greubel, May 11 2019
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[sum((-120)^j*binomial(n,j)*factorial(5*n-5*j) for j in (0..n)) for n in (1..20)] # G. C. Greubel, May 11 2019
A177840
Consider the n pairs (1,2), ..., (2n-1,2n); a(n) is the number of permutations of [ 2n ] with no two fixed points for any pair.
Original entry on oeis.org
1, 1, 21, 653, 37577, 3434169, 457819549, 83900098309, 20238575173137, 6217167231292913, 2369809434953636261, 1097587512530348834301, 607119566298408076479961, 395312612701784187384578473, 299298318246814086742418737197, 260721599469397754183307347278709
Offset: 0
a(2) = 21, because there are 4! = 24 permutations of [ 4 ], only 3 of them have pairs with 2 fixed points: [1,2,3,4], [1,2,4,3], [2,1,3,4].
a(3) = A(3,0) = 653, A(3,1) = 63, A(3,2) = 3, A(3,4) = 1, sum = 720 = 6!.
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f:= proc(n) option remember;
`if`(n<2, 1-n, (n-1) *(f(n-1)+f(n-2)))
end:
a:= n-> add(binomial(n,j) *2^j *f(2*n-j), j=0..n):
seq(a(n), n=0..20); # Alois P. Heinz, Sep 06 2011
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f[n_] := f[n] = If[n<2, 1-n, (n-1)*(f[n-1]+f[n-2])]; a[n_] := Sum[Binomial[ n, j]*2^j*f[2*n-j], {j, 0, n}]; Table[a[n], {n, 1, 20}] (* Jean-François Alcover, Feb 25 2017, after Alois P. Heinz *)
A375220
T(n,k) is the number of permutations of the multiset {1, 1, 2, 2, ..., n, n} with k occurrences of fixed pairs (j,j), where T(n,k), n >= 2, 0 <= k <= n-2 is a triangle read by rows.
Original entry on oeis.org
5, 74, 15, 2193, 296, 30, 101644, 10965, 740, 50, 6840085, 609864, 32895, 1480, 75, 630985830, 47880595, 2134524, 76755, 2590, 105, 76484389121, 5047886640, 191522380, 5692064, 153510, 4144, 140, 11792973495032, 688359502089, 22715489880, 574567140, 12807144, 276318, 6216, 180
Offset: 2
The triangle begins
5,
74, 15,
2193, 296, 30,
101644, 10965, 740, 50,
6840085, 609864, 32895, 1480, 75,
630985830, 47880595, 2134524, 76755, 2590, 105
Cf.
A375219 (similar for triples in the multiset).
Showing 1-6 of 6 results.
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