A143670
Array of higher spin alternating sign matrices, read by antidiagonals.
Original entry on oeis.org
1, 1, 1, 1, 2, 1, 1, 7, 3, 1, 1, 42, 26, 4, 1, 1, 429, 628, 70, 5, 1, 1, 7436, 41784, 5102, 155, 6, 1, 1, 218348, 7517457, 1507128, 28005
Offset: 1
The array begins:
========================================================
....|.r=0|..r=1.|.....r=2.|.......r=3.|..........r=4.|
n=1.|..1.|...1..|......1..|.........1.|...........1..|.A000012
n=2.|..1.|...2..|......3..|.........4.|...........5..|.A000027
n=3.|..1.|...7..|.....26..|........70.|.........155..|
n=4.|..1.|..42..|....628..|......5102.|.......28005..|
n=5.|..1.|.429..|..41784..|...1507128.|....28226084..|
n=6.|..1.|7436..|7517457..|1749710096.|152363972022..|
========================================================
Some terms of the 7th diagonal from
R. J. Mathar, Mar 04 2010
A180349
Gog words avoiding the subpattern 312.
Original entry on oeis.org
1, 2, 6, 26, 162, 1450, 18626, 343210, 9069306, 343611106, 18662952122, 1453016097506, 162144482866166, 25932885879826066
Offset: 1
For n=3, there are 7 Gog words: (1)(2)(3), (1)(3)(2), (2)(1)(3), (2)(3)(1), (3)(1)(2), (3)(2)(1) and (2)(123)(2). Of these, all but (3)(1)(2) avoid the subpattern 312.
More complicated examples: 31(234)3 and 25(12356)542 contain the subpattern 312 but 25(12456)532 does not.
- Arvind Ayyer, Robert Cori, and Dominique Gouyou-Beauchamps, Monotone triangles and 312 pattern avoidance, arXiv:1101.1666 [math.CO], 2011.
- Mathilde Bouvel, Rebecca Smith, and Jessica Striker, Key-avoidance for alternating sign matrices, arXiv:2408.05311 [math.CO], 2024. See p. 4.
- Ludovic Schwob, Sage program.
A229165
a(n) is the number of n X n matrices of 0's, 1's and -1's in which the entries in each row or column sum to 1 and there are no adjacent -1's or 1's in any row or column.
Original entry on oeis.org
1, 2, 7, 104, 7255, 2280064, 2708080414, 13039886441460
Offset: 1
Cf.
A050204 (entries in each row or column sum to 1).
A231499
Dimensions of totally primitive elements of Hopf algebra ASM.
Original entry on oeis.org
0, 1, 0, 2, 20, 277, 5776, 188900, 9980698, 868571406, 125895356788, 30578409431921, 12487049992168856, 8588968244025278785, 9960996172657038782698, 19489102605171036723471036, 64349079323905130216144033784, 358611512621756217468022899213127
Offset: 0
A293931
Number of circularly chained n-tuples of 2 X 2 alternating sign matrices.
Original entry on oeis.org
2, 10, 14, 42, 82, 214, 478, 1186, 2786
Offset: 1
- Heuer, Dylan, Chelsey Morrow, Ben Noteboom, Sara Solhjem, Jessica Striker, and Corey Vorland. "Chained permutations and alternating sign matrices - Inspired by three-person chess." Discrete Mathematics 340, no. 12 (2017): 2732-2752. Also arXiv:1611.03387.
A321511
Number of alternating sign n X n matrices excluding permutation matrices.
Original entry on oeis.org
0, 0, 0, 1, 18, 309, 6716, 213308, 10809896, 911472580, 129530643900, 31095704935575, 12611311380675900, 8639383512070631700, 9995541355360989190800, 19529076234659969430529200, 64427185703425668434106855840, 358869201916137601091798728321296
Offset: 0
- Michael De Vlieger, Table of n, a(n) for n = 0..93
- Paul Barry, Centered polygon numbers, heptagons and nonagons, and the Robbins numbers, arXiv:2104.01644 [math.CO], 2021.
- Paul Barry, Extensions of Riordan Arrays and Their Applications, Mathematics (2025) Vol. 13, No. 2, 242. See p. 8.
-
a[n_] := Product[(3 k + 1)!/(n + k)!, {k, 0, n-1}] - n!; a /@ Range[0, 17] (* Giovanni Resta, Nov 20 2018 *)
A102610
Triangle read by rows: coefficients of characteristic polynomials of lower triangular matrix of Robbins triangle numbers.
Original entry on oeis.org
0, 1, -1, 1, -2, 1, 1, -4, 5, -2, 1, -11, 33, -37, 14, 1, -53, 495, -1423, 1568, -588, 1, -482, 23232, -213778, 612035, -673260, 252252, 1, -7918, 3607384, -172966930, 1590265243, -4551765520, 5006613612, -1875745872, 1, -226266, 1732486848, -787838048562, 37768573496883, -347235787044084
Offset: 0
Lambert Klasen (lambert.klasen(AT)gmx.net) and Gary W. Adamson, Jan 30 2005
Generation of the triangle:
We begin with A048601
1
1 1
2 3 2
7 14 14 7
42 105 135 105 42
...
and get polynomials
x - 1
x^2 - 2*x + 1
x^3 - 4*x^2 + 5*x - 2
x^4 - 11*x^3 + 33*x^2 - 37*x + 14
x^5 - 53*x^4 + 495*x^3 - 1423*x^2 + 1568*x - 588
...
-
T(n, k) = binomial(n+k-2,k-1)*((2*n-k-1)!/(n-k)!)*prod(j=0,n-2,((3*j+1)!/(n+j)!))
RM(n)=M=matrix(n,n);for(l=1,n, for(k=1,l,M[l,k]=T(l,k)));M
for(i=1,10,print(charpoly(RM(i))))
Sequence has been prepended with a(0)=0 to enable table display (so offset has been set to 0 accordingly) by
Michel Marcus, Aug 23 2013
A134356
a(n) = Product_{k=1..n-1} (3k+1)!/(n+k)!.
Original entry on oeis.org
1, 4, 42, 1008, 51480, 5353920, 1100473920, 437480709120, 330886851724800, 470053968773760000, 1241242628123282400000, 6040838558884497984000000, 53797620867616662708672000000, 871394214986903051252166758400000
Offset: 1
-
a = {}; Do[k = Product[(3i + 1)!/(n + i)!, {i, 1, n - 1}]; AppendTo[a, k], {n, 1, 20}]; a
Table[Product[(3k+1)!/(n+k)!,{k,n-1}],{n,20}] (* Harvey P. Dale, Sep 30 2015 *)
A144017
Number of n X n X n alternating sign hypermatrices.
Original entry on oeis.org
1, 1, 2, 14, 924, 852960
Offset: 0
Samuel Zbarsky (sa_zbarsky(AT)yahoo.com), Sep 07 2008
For n = 1, the only n X n X n ASHM is [[[1]]].
For n = 2, the two n X n X n ASHMs are
[[[1,0],
[0,1]],
[[0,1],
[1,0]]]
and
[[[0,1],
[1,0]],
[[1,0],
[0,1]]].
-
# Program written in Sage
# Returns True if a given list of n n X n ASMs form an ASHM, returns False otherwise
def ASHM(L):
n = len(L)
# Searches through the vertical line in position (i,j) of the hypermatrix for each i and j
for i in range(n):
for j in range(n):
# Since the first nonzero entry in each line of an ASHM is +1, the alternating condition is checked
# as if the previous nonzero entry was -1
last = -1
for k in range(n):
# In each position of the current vertical line, if the sign of the current entry is the opposite
# of the previous, then the previous sign is updated
if L[k][i,j]*last == -1:
last *= -1
# Otherwise False is returned unless the current entry is 0
elif L[k][i,j] != 0:
return False
# If the most recent nonzero entry is not +1 by the time all entries have been checked, False is returned
if last != 1:
return False
# If False has not been returned, return True
return True
# Generates all combinations of one element from each list in L
def combos(L, current = [[]]):
# If there are no elements left which have not been combined, then return the combinations already made
if len(L) == 0:
return current
# Otherwise, each element of the next list in L is appended to the current list of combinations made
output = []
for K in current:
for a in L[0]:
output.append(K + [a])
return combos(L[1:], output)
# Counts all ASHMs of order n
def count_ASHMs(n):
# All ASMs of order n are imported as matrices
asms = []
for A in AlternatingSignMatrices(n):
asms.append(A.to_matrix())
# Initially, zero ASHMs have been counted
count = 0
# Every possible combination of n n X n ASMs is checked
for i in combos([[k for k in range(len(asms))] for m in range(n)]):
# If the current list of n n X n ASMs forms an ASHM, then it is counted
count += int(ASHM([asms[i[k]] for k in range(n)]))
# The final count is returned
return count
# Note: I ran a more efficient version of this program in Python to obtain the answer for n=5, and even then it took 6 hours.
print(count_ASHMs(0))
print(count_ASHMs(1))
print(count_ASHMs(2))
print(count_ASHMs(3))
print(count_ASHMs(4))
print(count_ASHMs(5))
# Cian O'Brien, May 31 2023
a(4) corrected and a(5) added, and definition updated by
Cian O'Brien, May 31 2023
A155901
Arise in p-adic valuations of sequences counting alternating sign matrices.
Original entry on oeis.org
2, 8, 5, 12, 5, 14, 8, 14
Offset: 1
a(7) = 8 because "the eight solutions to Nu(T(n)) = 7 are 26, 38, 46, 82, 5462, 10922, 10924 and J_15 - 1 = 21844" where J_k = k-th Jacobsthal number = A001045(k).
- D. Bressoud, Proofs and Confirmations: the story of the Alternating Sign Matrix Conjecture, Cambridge University Press, 1999.
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