cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A327410 Numbers represented by the partition coefficients of prime partitions.

Original entry on oeis.org

1, 6, 10, 20, 21, 36, 56, 78, 90, 105, 120, 171, 210, 252, 300, 364, 465, 528, 560, 741, 756, 792, 903, 990, 1140, 1176, 1485, 1540, 1680, 1830, 1953, 1980, 2346, 2520, 2600, 2628, 2775, 3240, 3432, 3570, 4095, 4368, 4851, 4960, 5253, 5460, 5886, 5984, 6105
Offset: 1

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Author

Peter Luschny, Sep 07 2019

Keywords

Comments

Given a partition pi = (p1, p2, p3, ...) we call the associated multinomial coefficient (p1+p2+ ...)! / (p1!*p2!*p3! ...) the 'partition coefficient' of pi and denote it by . We say 'k is represented by pi' if k = .
A partition is a prime partition if all parts are prime.

Examples

			(2*n)!/2^n (for n >= 1) is a subsequence because [2,2,...,2] (n times '2') is a prime partition. Similarly A327411(n) is a subsequence because [3,2,2,...,2] (n times '2') is a prime partition. (3*n)!/(6^n) and A327412 are subsequences for the same reason.
The representations are not unique. 1 is the represented by all partitions of the form [p], p prime. For example 210 is represented by [3, 2, 2] and by [19, 2]. The list below shows the partitions with the smallest sum.
1   <- [2],
6   <- [2, 2],
10  <- [3, 2],
20  <- [3, 3],
21  <- [5, 2],
36  <- [7, 2],
56  <- [5, 3],
78  <- [11, 2],
90  <- [2, 2, 2],
105 <- [13, 2],
120 <- [7, 3],
171 <- [17, 2],
210 <- [3, 2, 2],
252 <- [5, 5],
300 <- [23, 2].
		

Crossrefs

Programs

  • SageMath
    def A327410_list(n):
        res = []
        for k in range(2*n):
            P = Partitions(k, parts_in = prime_range(k+1))
            res += [multinomial(p) for p in P]
        return sorted(Set(res))[:n]
    print(A327410_list(20))

A358112 Table read by rows. A statistic of permutations of the multiset {1,1,2,2,...,n,n}.

Original entry on oeis.org

1, 5, 1, 47, 42, 1, 641, 1659, 219, 1, 11389, 72572, 28470, 968, 1, 248749, 3610485, 3263402, 357746, 4017, 1, 6439075, 204023334, 371188155, 95559940, 3853617, 16278, 1, 192621953, 12989570167, 43844432805, 22448025251, 2216662051, 38270373, 65399, 1
Offset: 1

Views

Author

Peter Luschny, Oct 30 2022

Keywords

Comments

Table 1, page 12 in Maazouz and Pitman (note a typo in T(2, 0)).

Examples

			[n\d]    0            1           2           3           4           5     6
-----------------------------------------------------------------------------
[1]         1;
[2]         5,           1;
[3]        47,          42,           1;
[4]       641,        1659,         219,           1;
[5]     11389,       72572,       28470,         968,          1;
[6]    248749,     3610485,     3263402,      357746,       4017,        1;
[7]   6439075,   204023334,   371188155,    95559940,    3853617,    16278, 1
[8] 192621953, 12989570167, 43844432805, 22448025251, 2216662051, 38270373,
65399, 1
		

Crossrefs

Cf. A006902 (row 0), A000680 (row sums).

Programs

  • Maple
    P := (n, x) -> (2*n)!*add(add(binomial(n, k)*binomial(n-k, j)*
    (-1)^(n-k-j)*max(x - k, 0)^(2*n - j)/(2*n - j)!, j = 0..n-k), k = 0..n):
    Trow := n -> seq(P(n, k+1) - P(n, k), k = 0..n-1):
    seq(print(Trow(n)), n = 1..8);

Formula

T(n, k) = P(n, k+1) - P(n, k), where P(n, x) = (2*n)!*Sum_{k=0..n} Sum_{j=0..n-k} binomial(n, k)*binomial(n-k, j)*(-1)^(n-k-j)*max(x - k, 0)^(2*n - j)/(2*n - j)!.

A368028 Square array read by antidiagonals; T(n,k) = number of ways a vehicle with capacity k can transport n distinct individuals with distinct starting and finishing points.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 1, 1, 0, 6, 6, 1, 1, 0, 24, 54, 6, 1, 1, 0, 120, 648, 90, 6, 1, 1, 0, 720, 9720, 1944, 90, 6, 1, 1, 0, 5040, 174960, 52920, 2520, 90, 6, 1, 1, 0, 40320, 3674160, 1730160, 99000, 2520, 90, 6, 1, 1, 0, 362880, 88179840, 65998800, 4806000, 113400, 2520, 90, 6, 1, 1, 0, 3628800, 2380855680, 2877275520, 274050000, 6966000, 113400, 2520, 90, 6, 1, 1
Offset: 0

Views

Author

Henry Bottomley, Dec 24 2023

Keywords

Examples

			T(3,2)=54 represented by the nine patterns AABBCC, AABCBC, AABCCB, ABABCC, ABACBC, ABACCB, ABBACC, ABBCAC, ABBCCA multiplied by 3!=6 for the permutations of A,B,C; but for example ABCABC would not work as the vehicle would be over its capacity of 2 after picking up 3 passengers.
		

Crossrefs

Cf. A080934. Rows include A000012, A057427. Columns include A000007, A000142, A034001. Diagonals include A000680 and A071798.

Formula

If f(n,k,c)=n*f(n-1,k,c+1)+c*f(n,k,c-1) with f(n,k,c)=0 when n<0 or k<0 or c<0 or k

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

Author

Hugo Pfoertner, Aug 08 2024

Keywords

Examples

			The triangle begins
          5,
         74,       15,
       2193,      296,      30,
     101644,    10965,     740,    50,
    6840085,   609864,   32895,  1480,   75,
  630985830, 47880595, 2134524, 76755, 2590, 105
		

Crossrefs

Cf. A000217, A000680, A028895, A116218, A374980 (column 0), A375222 (column 1), A375223.
Cf. A375219 (similar for triples in the multiset).

Programs

  • PARI
    \\ using functions mima and a375219 from A375219, row n of triangle:
    a375219(n,sizeb=2)

Formula

T(n,n) = 1, T(n,n-1) = 0 (terms not in DATA),
T(n,n-2) = 5*n*(n-1)/2 = 5*A000217(n-1) = A028895(n-1),
Sum_{j=0..n-2} T(n,j) = (2*n)!/(2^n) - 1 = A000680(n) - 1,
Sum_{j=1..n-2} T(n,j) = A375223(n) - 1.
Previous Showing 81-84 of 84 results.