A141598
Total number of all-interval rows for systems with 2n notes in the octave (2n-edo).
Original entry on oeis.org
2, 8, 24, 192, 2880, 46272, 1250592, 44095488, 1865756160
Offset: 1
Milan Gustar (artech(AT)noise.cz), Sep 03 2008
A067601
a(n) is the number of inequivalent permutations of {0..2n-1}, such that the first differences (modulo 2n) are a permutation of {1..2n-1}.
Original entry on oeis.org
1, 1, 2, 12, 144, 1928, 44664, 1377984, 51826560
Offset: 1
Eugene McDonnell (eemcd(AT)aol.com), Jan 31 2002
0 1 3 2 has first difference, mod 4, of 1 2 3;
0 2 1 4 5 3 has first difference, mod 6, of 2 5 3 1 4;
0 4 5 8 3 1 7 9 2 11 10 6 has first difference, mod 12, of 4 1 3 7 10 6 2 5 9 11 8.
A155914
Example of an all interval series: the 12 integers 0..11 sorted such that the first differences contain all numbers from 1 to 11 (mod 12).
Original entry on oeis.org
0, 11, 7, 4, 2, 9, 3, 8, 10, 1, 5, 6
Offset: 1
Craig Bourne (cbourne(AT)cbourne.com), Jan 30 2009
- Robert Morris and Daniel Starr, The Structure of All-Interval Series, 1974, Yale University Department of Music.
A238838
Number of 2n X 2n addition squares in which every digram (s,s;), s' != s, appears once horizontally and once vertically.
Original entry on oeis.org
2, 48, 5760, 5806080, 75246796800, 1780537083494400, 115939740156316876800, 19864514173849162481664000
Offset: 1
A322253
Number of circular permutations of the integers from 0 to n which generate a complete stepping-on sequence, when the stepping-on direction depends on the odd/even parity of the current value.
Original entry on oeis.org
1, 2, 2, 4, 4, 48, 24, 32, 288, 3072, 3856, 38272, 89328, 1294080
Offset: 1
a(2n - 1) =
A141599(n) for n up to 7, again limited by available computing power. It is conjectured that the correspondence continues indefinitely.
A364237
a(n) is the number of non-equivalent permutations of {1,2,...,2n-1} such that no subset of consecutive terms from the permutation sums to 0 modulo 2n, where two permutations are equivalent if one can be obtained from the other by multiplying every entry with an integer relatively prime to 2n and/or reversing the permutation.
Original entry on oeis.org
1, 1, 2, 4, 42, 504, 7492, 172480, 8639632
Offset: 1
When n=3, there are four permutations of {1,2,3,4,5} such that no subset of consecutive terms from the permutation sums to 0 modulo 6, namely 14325, 25314, 41352, and 52341. Note that 14325 and 52341 are equivalent by reversing the permutations. Furthermore multiplication by 5 on every entry also yields the same equivalence. Additionally, 25314 and 41352 are analogously equivalent. Hence a(3)=2.
When n=4, 6142573 and 3752416 are equivalent by reversing the permutations but not by multiplying any integer relatively prime to 8, whereas 6142573 and 2346751 are equivalent by multiplication of 3 on every entry.
-
n = 3 #the index for the sequence a(n)
orbits = {} #dictionary of permutations that are consecutive zero-sum-free
seen = [] #list of seen permutations that are consecutive zero-sum-free
a = 0 #the value of a(n)
for labeling in Permutations(range(1,2*n)):
if labeling not in seen:
sums = [labeling[0]]
for i in range(1,2*n-1):
nextsum = (labeling[i] + sums[i-1]) % (2*n)
if any([nextsum == 0, nextsum in sums]):
break
sums.append(nextsum)
if len(sums) == (2*n)-1:
a += 1
orbits[a] = []
for m in [x for x in range(1,2*n) if gcd(x,2*n) == 1]:
equiv = [(m*labeling[i]) % (2*n) for i in range(2*n-1)]
if equiv not in orbits[a]:
orbits[a].append(equiv)
seen.append(equiv)
equiv = [equiv[2*n-2-i] for i in range(2*n-1)]
if equiv not in orbits[a]:
orbits[a].append(equiv)
seen.append(equiv)
print(f"a({n}) = {a}\n")
print("Equivalencies:")
for i in range(1,a+1):
print(f"{i}.")
for x in orbits[i]:
print(x)
print('\n')
Showing 1-6 of 6 results.
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