A322013
Square array A(n,k), n >= 1, k >= 1, read by antidiagonals, where A(n,k) is the number of permutations of n copies of 1..k introduced in order 1..k with no element equal to another within a distance of 1.
Original entry on oeis.org
1, 1, 0, 1, 1, 0, 1, 5, 1, 0, 1, 36, 29, 1, 0, 1, 329, 1721, 182, 1, 0, 1, 3655, 163386, 94376, 1198, 1, 0, 1, 47844, 22831355, 98371884, 5609649, 8142, 1, 0, 1, 721315, 4420321081, 182502973885, 66218360625, 351574834, 56620, 1, 0
Offset: 1
Square array begins:
1, 1, 1, 1, 1, 1, ...
0, 1, 5, 36, 329, 3655, ...
0, 1, 29, 1721, 163386, 22831355, ...
0, 1, 182, 94376, 98371884, 182502973885, ...
0, 1, 1198, 5609649, 66218360625, 1681287695542855, ...
0, 1, 8142, 351574834, 47940557125969, 16985819072511102549, ...
- Seiichi Manyama, Antidiagonals n = 1..53, flattened
- Evgeniy Krasko, Igor Labutin, and Alexander Omelchenko, Enumeration of Labelled and Unlabelled Hamiltonian Cycles in Complete k-partite Graphs, arXiv:1709.03218 [math.CO], 2017.
- Mathematics.StackExchange, Find the number of k 1's, k 2's, ... , k n's - total kn cards, Apr 08 2012.
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q(n,x) = sum(i=1, n, (-1)^(n-i) * binomial(n-1, n-i) * x^i/i!)
T(n,k) = subst(serlaplace(q(n,x)^k), x, 1)/k! \\ Andrew Howroyd, Feb 03 2024
A190830
Number of permutations of 4 copies of 1..n introduced in order 1..n with no element equal to another within a distance of 1.
Original entry on oeis.org
1, 0, 1, 182, 94376, 98371884, 182502973885, 551248360550999, 2536823683737613858, 16904301142107043464659, 156690501089429126239232946, 1955972150994131850032960933480, 32016987304767134806200915633253966, 672058204939482014438623912695190927357
Offset: 0
Some solutions for n=3:
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
3 1 3 3 1 3 3 3 3 3 3 1 1 3 1 1
1 2 2 2 2 2 2 1 1 2 1 3 3 1 3 2
2 3 3 3 1 1 3 2 2 3 2 1 2 3 1 1
3 2 1 2 3 2 1 3 1 1 3 2 3 2 2 3
1 3 2 3 2 3 3 1 3 2 2 3 2 1 3 1
3 2 3 1 3 1 2 3 1 1 1 2 1 3 2 3
1 1 1 3 1 3 1 2 2 3 3 3 2 2 3 2
2 3 2 1 3 2 3 1 3 1 1 2 3 3 1 3
3 1 1 2 2 3 1 3 2 2 2 3 1 1 3 2
2 3 3 1 3 1 2 2 3 3 3 1 3 2 2 3
A348813
a(n) = number of chord labeled loopless diagrams by number of K_3.
Original entry on oeis.org
0, 1, 22, 1415, 140343, 20167651, 3980871156, 1035707510307, 343866839138005, 141979144588872613, 71386289535825383386, 42954342000612934599071, 30482693813120122213093587, 25196997894058490607106028095, 24001522306527907199721466108488, 26102037346800387738363882455862531
Offset: 1
A193624
Number of ways n triples can sit in a row without any siblings next to each other.
Original entry on oeis.org
1, 0, 72, 37584, 53529984, 152458744320, 766958183193600, 6236531290739312640, 76788695692068062330880, 1361934174627779827740180480, 33454092372947487842682293452800, 1102556254139040688616563751190528000
Offset: 0
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B:=Binomial;
f:= func< n,j | (&+[B(n,k)*B(2*k,j)*(-3)^(n+k-j): k in [Ceiling(j/2)..n]]) >;
A193624:= func< n | (&+[Factorial(n+j)*f(n,j): j in [0..2*n]]) >;
[A193624(n): n in [0..30]]; // G. C. Greubel, Sep 22 2023
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A193624[n_]:= Sum[(n+j)!*Binomial[n,k]*Binomial[2*k,j]*(-3)^(n+k-j), {j,0,2*n}, {k,Ceiling[j/2],n}];
Array[A193624, 30, 0] (* G. C. Greubel, Sep 22 2023 *)
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b=binomial;
def f(j,n): return sum(b(n,k)*b(2*k,j)*(-3)^(n+k-j) for k in range((j//2),n+1))
def A193624(n): return sum(factorial(n+j)*f(j,n) for j in range(2*n+1))
[A193624(n) for n in range(31)] # G. C. Greubel, Sep 22 2023
A193638
Number of permutations of the multiset {1,1,1,2,2,2,3,3,3,...,n,n,n} with no two consecutive terms equal.
Original entry on oeis.org
1, 0, 2, 174, 41304, 19606320, 16438575600, 22278418248240, 45718006789687680, 135143407245840698880, 553269523327347306412800, 3039044104423605600086688000, 21819823367694505460651694873600, 200345011881335747639978525387827200
Offset: 0
a(2) = 2 because there are two permutations of {1,1,1,2,2,2} avoiding equal consecutive terms: 121212 and 212121.
Cf.
A114938 = similar, with two copies instead of three.
Cf.
A193624 = arrangements of triples with no adjacent siblings.
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B:=Binomial;
f:= func< n,j | (&+[B(n,k)*B(2*k,j)*(-3)^(k-j): k in [Ceiling(j/2)..n]]) >;
A193638:= func< n | (-1/2)^n*(&+[Factorial(n+j)*f(n,j): j in [0..2*n]]) >;
[A193638(n): n in [0..30]]; // G. C. Greubel, Sep 22 2023
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a:= proc(n) option remember; `if`(n<3, (n-1)*(3*n-2)/2,
n*((3*n-1)*(3*n^2-5*n+4) *a(n-1) +2*(n-1)*(6*n^2-9*n-1) *a(n-2)
-4*n*(n-1)*(n-2) *a(n-3))/(2*n-2))
end:
seq(a(n), n=0..20); # Alois P. Heinz, Jun 05 2013
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a[n_]:= (1/6^n)*Sum[(n+j)!*Binomial[n, k]*Binomial[2k, j]*(-3)^(n+k-j), {j,0,2n}, {k, Ceiling[j/2], n}]; Table[a[n], {n, 0, 13}] (* Jean-François Alcover, Jul 22 2017, after Tani Akinari *)
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a(n):= (1/6^n)*sum((n+j)!*sum(binomial(n,k)*binomial(2*k,j)* (-3)^(n+k-j), k,ceiling(j/2),n), j,0,2*n); /* Tani Akinari, Sep 23 2012 */
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from sympy.core.cache import cacheit
@cacheit
def a(n): return (n-1)*(3*n-2)//2 if n<3 else n*((3*n-1)*(3*n**2 - 5*n + 4)*a(n-1) + 2*(n-1)*(6*n**2 -9*n-1)*a(n-2) - 4*n*(n-1)*(n-2)*a(n- 3))//(2*n-2)
print([a(n) for n in range(51)]) # Indranil Ghosh, Jul 22 2017, formula after Maple code
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b=binomial;
def f(j,n): return sum(b(n,k)*b(2*k,j)*(-3)^(k-j) for k in range((j//2),n+1))
def A193638(n): return (-1/2)^n*sum(factorial(n+j)*f(j,n) for j in range(2*n+1))
[A193638(n) for n in range(31)] # G. C. Greubel, Sep 22 2023
A321666
Number of arrangements of n 1's, n 2's, ..., n n's avoiding equal consecutive terms and introduced in ascending order.
Original entry on oeis.org
1, 1, 1, 29, 94376, 66218360625, 16985819072511102549, 2421032324142610480402567434373, 271259741131895052775392614041761701799270286, 32119646666355552112999645991677870426882424139287301894021793
Offset: 0
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{a(n) = sum(i=n, n^2, i!*polcoef(sum(j=1, n, (-1)^(n-j)*binomial(n-1, j-1)*x^j/j!)^n, i))/n!} \\ Seiichi Manyama, May 27 2019
A321669
Number of permutations of 9 copies of 1..n introduced in order 1..n with no element equal to another within a distance of 1.
Original entry on oeis.org
1, 0, 1, 2872754, 104650147201049, 23575497690601916022516, 24302858067615766089801166488125, 91155245844064069307740171414201519055298, 1046031892354833895113128900608177633584652958677057, 32119646666355552112999645991677870426882424139287301894021793
Offset: 0
A321670
Number of permutations of 10 copies of 1..n introduced in order 1..n with no element equal to another within a distance of 1.
Original entry on oeis.org
1, 0, 1, 20824778, 7279277647839552, 19672658572012343899666292, 293736218147318801678882792470437721, 18739368045280595665934917472507368174737872589, 4204427313459831775866154680419213479057724331798640498651
Offset: 0
A348814
a(n) = number of loopless diagrams by number of K_3 up to rotational symmetry.
Original entry on oeis.org
0, 1, 4, 126, 9367, 1120780, 189565588, 43154533233, 12735808866899, 4732638168795171, 2163220895025390670, 1193176166690983987122, 781607533669746761791541
Offset: 1
Showing 1-9 of 9 results.
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