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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A217327 Number of self-inverse permutations in S_n with longest increasing subsequence of length 7.

Original entry on oeis.org

1, 7, 55, 319, 1904, 10275, 56135, 294386, 1556323, 8086433, 42298721, 219795160, 1149139210, 5999688692, 31506046052, 165664633982, 875886376212, 4643488263933, 24746018418741, 132328997879066, 711142850556217, 3836134976520394, 20791024498584110
Offset: 7

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Author

Alois P. Heinz, Sep 30 2012

Keywords

Comments

Also the number of Young tableaux with n cells and 7 rows.

Examples

			a(7) = 1: 1234567.
a(8) = 7: 12345687, 12345768, 12346578, 12354678, 12435678, 13245678, 21345678.
		

Crossrefs

Column k=7 of A047884.

Formula

a(n) = A182172(n,7)-A182172(n,6) = A007578(n)-A007579(n).

A218267 Number of standard Young tableaux of n cells and height >= 7.

Original entry on oeis.org

1, 8, 64, 400, 2465, 14092, 80016, 442248, 2442351, 13375366, 73477622, 403703404, 2230591660, 12380801756, 69225756076, 389806286920, 2213844625658, 12681996193252, 73339826141716, 428242854338216, 2526129602115517, 15056977593085444, 90712249806247400
Offset: 7

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Author

Alois P. Heinz, Oct 24 2012

Keywords

Comments

Also number of self-inverse permutations in S_n with longest increasing subsequence of length >= 7. a(7)=1: 1234567; a(8)=8: 12345678, 12345687, 12345768, 12346578, 12354678, 12435678, 13245678, 21345678.

Crossrefs

Column k=7 of A182222.

Programs

  • Maple
    b:= proc(n) b(n):= `if`(n<2, 1, b(n-1) +(n-1)*b(n-2)) end:
    g:= proc(n) option remember;
          `if`(n<4, [1, 1, 2, 4][n+1], ((20*n^2+184*n+336)*g(n-1)
           +4*(n-1)*(10*n^2+58*n+33)*g(n-2) -144*(n-1)*(n-2)*g(n-3)
           -144*(n-1)*(n-2)*(n-3)*g(n-4)) / ((n+5)*(n+8)*(n+9)))
        end:
    a:= n-> b(n) -g(n):
    seq(a(n), n=7..30);

Formula

a(n) = A000085(n) - A007579(n) = A182172(n,n) - A182172(n,6).

A229068 Number of standard Young tableaux of n cells and height <= 12.

Original entry on oeis.org

1, 1, 2, 4, 10, 26, 76, 232, 764, 2620, 9496, 35696, 140152, 568503, 2390466, 10349340, 46204720, 211779200, 997134592, 4808141824, 23745792032, 119848119307, 618058083314, 3251373425356, 17442275104496, 95297400355320, 530067682582320, 2998503402985440
Offset: 0

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Author

Vaclav Kotesovec, Sep 12 2013

Keywords

Comments

Conjecture: generally (for tableaux with height <= k), a(n) ~ k^n/Pi^(k/2) * (k/n)^(k*(k-1)/4) * Product_{j=1..k} Gamma(j/2); set k=12 for this sequence.

Crossrefs

Cf. A182172, A001405 (k=2), A001006 (k=3), A005817 (k=4), A049401 (k=5), A007579 (k=6), A007578 (k=7), A007580 (k=8), A212915 (k=9), A212916 (k=10), A229053 (k=11).
Column k=12 of A182172.

Programs

  • Mathematica
    RecurrenceTable[{-147456 (-5+n) (-4+n) (-3+n) (-2+n) (-1+n) (12+n) a[-6+n]-110592 (-4+n) (-3+n) (-2+n) (-1+n) (29+2 n) a[-5+n]+256 (-3+n) (-2+n) (-1+n) (121272+32786 n+2343 n^2+49 n^3) a[-4+n]+128 (-2+n) (-1+n) (438597+90321 n+5391 n^2+98 n^3) a[-3+n]-16 (-1+n) (8718630+5347213 n+804616 n^2+49754 n^3+1372 n^4+14 n^5) a[-2+n]-8 (27335490+10162354 n+1206473 n^2+63328 n^3+1533 n^4+14 n^5) a[-1+n]+(11+n) (20+n) (27+n) (32+n) (35+n) (36+n) a[n]==0, a[1]==1, a[2]==2, a[3]==4, a[4]==10, a[5]==26, a[6]==76}, a, {n, 20}]

Formula

Recurrence: (n+11)*(n+20)*(n+27)*(n+32)*(n+35)*(n+36)*a(n) = 8*(14*n^5 + 1533*n^4 + 63328*n^3 + 1206473*n^2 + 10162354*n + 27335490)*a(n-1) + 16*(n-1)*(14*n^5 + 1372*n^4 + 49754*n^3 + 804616*n^2 + 5347213*n + 8718630)*a(n-2) - 128*(n-2)*(n-1)*(98*n^3 + 5391*n^2 + 90321*n + 438597)*a(n-3) - 256*(n-3)*(n-2)*(n-1)*(49*n^3 + 2343*n^2 + 32786*n + 121272)*a(n-4) + 110592*(n-4)*(n-3)*(n-2)*(n-1)*(2*n + 29)*a(n-5) + 147456*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*(n+12)*a(n-6).
a(n) ~ 602791875/128 * 12^(n+33)/(Pi^3*n^33).
Previous Showing 11-13 of 13 results.