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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A352516 Number of excedances (parts above the diagonal) of the n-th composition in standard order.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1
Offset: 0

Views

Author

Gus Wiseman, Mar 23 2022

Keywords

Comments

The k-th composition in standard order (graded reverse-lexicographic, A066099) is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again. This gives a bijective correspondence between nonnegative integers and integer compositions. See also A000120, A059893, A070939, A114994, A225620.

Examples

			The 5392th composition in standard order is (2,2,4,5), with excedances {1,3,4}, so a(5392) = 3.
		

Crossrefs

Positions of first appearances are A104462.
The opposite version is A352514, counted by A352521 (first column A219282).
The weak opposite version is A352515, counted by A352522 (first A238874).
The weak version is A352517, counted by A352525 (first column A177510).
The triangle A352524 counts these compositions (first column A008930).
A008292 is the triangle of Eulerian numbers (version without zeros).
A011782 counts compositions.
A173018 counts permutations by number of excedances, weak A123125.
A238349 counts comps by fixed points, first col A238351, rank stat A352512.
A352487 is the excedance set of A122111.
A352523 counts comps by unfixed points, first A010054, rank stat A352513.

Programs

  • Mathematica
    stc[n_]:=Differences[Prepend[Join@@ Position[Reverse[IntegerDigits[n,2]],1],0]]//Reverse;
    pd[y_]:=Length[Select[Range[Length[y]],#
    				

A352517 Number of weak excedances (parts on or above the diagonal) of the n-th composition in standard order.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 2, 2, 2, 2, 3, 2, 2
Offset: 0

Views

Author

Gus Wiseman, Mar 23 2022

Keywords

Comments

The k-th composition in standard order (graded reverse-lexicographic, A066099) is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again. This gives a bijective correspondence between nonnegative integers and integer compositions. See also A000120, A059893, A070939, A114994, A225620.

Examples

			The 169th composition in standard order is (2,2,3,1), with weak excedances {1,2,3}, so a(169) = 3.
		

Crossrefs

Positive positions of first appearances are A164894.
The version for partitions is A257990.
The strong opposite version is A352514, counted by A352521 (first A219282).
The opposite version is A352515, counted by A352522 (first column A238874).
The strong version is A352516, counted by A352524 (first column A008930).
The triangle A352525 counts these compositions (first column A177510).
A008292 is the triangle of Eulerian numbers (version without zeros).
A011782 counts compositions.
A173018 counts permutations by number of excedances, weak A123125.
A238349 counts comps by fixed points, first col A238351, rank stat A352512.
A352489 is the weak excedance set of A122111.
A352523 counts comps by unfixed points, first A010054, rank stat A352513.

Programs

  • Mathematica
    stc[n_]:=Differences[Prepend[Join@@ Position[Reverse[IntegerDigits[n,2]],1],0]]//Reverse;
    pdw[y_]:=Length[Select[Range[Length[y]],#<=y[[#]]&]];
    Table[pdw[stc[n]],{n,0,30}]

A352829 Number of strict integer partitions y of n with a fixed point y(i) = i.

Original entry on oeis.org

0, 1, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 23, 26, 30, 36, 42, 50, 60, 70, 82, 96, 110, 126, 144, 163, 184, 208, 234, 264, 298, 336, 380, 430, 486, 550, 622, 702, 792, 892, 1002, 1125, 1260, 1408, 1572, 1752, 1950, 2168, 2408, 2672
Offset: 0

Views

Author

Gus Wiseman, May 15 2022

Keywords

Examples

			The a(11) = 2 through a(17) = 12 partitions (A-F = 10..15):
  (92)   (A2)   (B2)    (C2)    (D2)     (E2)     (F2)
  (821)  (543)  (643)   (653)   (753)    (763)    (863)
         (921)  (A21)   (743)   (843)    (853)    (953)
                (5431)  (B21)   (C21)    (943)    (A43)
                        (5432)  (6432)   (D21)    (E21)
                        (6431)  (6531)   (6532)   (7532)
                                (7431)   (7432)   (7631)
                                (54321)  (7531)   (8432)
                                         (8431)   (8531)
                                         (64321)  (9431)
                                                  (65321)
                                                  (74321)
		

Crossrefs

The non-strict version is A001522 (unproved, ranked by A352827 or A352874).
The version for permutations is A002467, complement A000166.
The reverse version is A096765 (or A025147 shifted right once).
The non-strict reverse version is A238395, ranked by A352872.
The complement is counted by A352828, non-strict A064428 (unproved, ranked by A352826 or A352873).
The version for compositions is A352875, complement A238351.
A000041 counts partitions, strict A000009.
A000700 counts self-conjugate partitions, ranked by A088902.
A008290 counts permutations by fixed points, unfixed A098825.
A115720 and A115994 count partitions by their Durfee square.
A238349 counts compositions by fixed points, complement A352523.
A238352 counts reversed partitions by fixed points, rank statistic A352822.
A238394 counts reversed partitions without a fixed point, ranked by A352830.
A352833 counts partitions by fixed points.

Programs

  • Mathematica
    pq[y_]:=Length[Select[Range[Length[y]],#==y[[#]]&]];
    Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&pq[#]>0&]],{n,0,30}]

Formula

G.f.: Sum_{n>=1} q^(n*(3*n-1)/2)*Product_{k=1..n-1} (1+q^k)/(1-q^k). - Jeremy Lovejoy, Sep 26 2022

A164864 Number of ways of placing n labeled balls into 10 indistinguishable boxes; word structures of length n using a 10-ary alphabet.

Original entry on oeis.org

1, 1, 2, 5, 15, 52, 203, 877, 4140, 21147, 115975, 678569, 4213530, 27641927, 190829797, 1381367941, 10448276360, 82285618467, 672294831619, 5676711562593, 49344452550230, 439841775811967, 4005444732928641, 37136385907400125, 349459367068932740
Offset: 0

Views

Author

Alois P. Heinz, Aug 28 2009

Keywords

Crossrefs

Programs

  • Maple
    # First program:
    a:= n-> ceil(2119/11520*2^n +103/1680*3^n +53/3456*4^n +11/3600*5^n +6^n/1920 +7^n/15120 +8^n/80640 +10^n/3628800): seq(a(n), n=0..25);
    # second program:
    a:= n-> add(Stirling2(n, k), k=0..10): seq(a(n), n=0..25);
  • Mathematica
    Table[Sum[StirlingS2[n,k],{k,0,10}],{n,0,30}] (* Harvey P. Dale, Nov 22 2023 *)

Formula

a(n) = Sum_{k=0..10} Stirling2 (n,k).
a(n) = ceiling(2119/11520*2^n +103/1680*3^n +53/3456*4^n +11/3600*5^n +6^n/1920 +7^n/15120 +8^n/80640 +10^n/3628800).
G.f.: (148329*x^9 -613453*x^8 +855652*x^7 -596229*x^6 +240065*x^5 -59410*x^4 +9177*x^3 -862*x^2 +45*x-1) / ((10*x-1) *(8*x-1) *(7*x-1) *(6*x-1) *(5*x-1) *(4*x-1) *(3*x-1) *(2*x-1) *(x-1)).
a(n) <= A000110(n) with equality only for n <= 10.

A352831 Numbers whose weakly increasing prime indices y have exactly one fixed point y(i) = i.

Original entry on oeis.org

2, 4, 8, 9, 10, 12, 14, 16, 22, 24, 26, 27, 28, 32, 34, 36, 38, 40, 44, 46, 48, 52, 58, 60, 62, 63, 64, 68, 70, 72, 74, 75, 76, 80, 81, 82, 86, 88, 92, 94, 96, 98, 99, 104, 106, 108, 110, 112, 116, 117, 118, 120, 122, 124, 125, 128, 130, 132, 134, 135, 136
Offset: 1

Views

Author

Gus Wiseman, Apr 08 2022

Keywords

Comments

A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.

Examples

			The terms together with their prime indices begin:
      2: {1}             36: {1,1,2,2}         74: {1,12}
      4: {1,1}           38: {1,8}             75: {2,3,3}
      8: {1,1,1}         40: {1,1,1,3}         76: {1,1,8}
      9: {2,2}           44: {1,1,5}           80: {1,1,1,1,3}
     10: {1,3}           46: {1,9}             81: {2,2,2,2}
     12: {1,1,2}         48: {1,1,1,1,2}       82: {1,13}
     14: {1,4}           52: {1,1,6}           86: {1,14}
     16: {1,1,1,1}       58: {1,10}            88: {1,1,1,5}
     22: {1,5}           60: {1,1,2,3}         92: {1,1,9}
     24: {1,1,1,2}       62: {1,11}            94: {1,15}
     26: {1,6}           63: {2,2,4}           96: {1,1,1,1,1,2}
     27: {2,2,2}         64: {1,1,1,1,1,1}     98: {1,4,4}
     28: {1,1,4}         68: {1,1,7}           99: {2,2,5}
     32: {1,1,1,1,1}     70: {1,3,4}          104: {1,1,1,6}
     34: {1,7}           72: {1,1,1,2,2}      106: {1,16}
For example, 63 is in the sequence because its prime indices {2,2,4} have a unique fixed point at the second position.
		

Crossrefs

* = unproved
These are the positions of 1's in A352822.
*The reverse version for no fixed points is A352826, counted by A064428.
*The reverse version is A352827, counted by A001522 (strict A352829).
The version for no fixed points is A352830, counted by A238394.
These partitions are counted by A352832, compositions A240736.
Allowing more than one fixed point gives A352872, counted by A238395.
A000700 counts self-conjugate partitions, ranked by A088902.
A001222 counts prime indices, distinct A001221.
A008290 counts permutations by fixed points, nonfixed A098825.
A056239 adds up prime indices, row sums of A112798 and A296150.
A115720 and A115994 count partitions by their Durfee square.
A238349 counts compositions by fixed points, complement A352523.
A238352 counts reversed partitions by fixed points.
A352833 counts partitions by fixed points.

Programs

  • Mathematica
    pq[y_]:=Length[Select[Range[Length[y]],#==y[[#]]&]];
    Select[Range[100],pq[Flatten[Cases[FactorInteger[#],{p_,k_}:>Table[PrimePi[p],{k}]]]]==1&]

A352520 Number of integer compositions y of n with exactly one nonfixed point y(i) != i.

Original entry on oeis.org

0, 0, 2, 1, 4, 5, 3, 7, 8, 9, 6, 11, 12, 13, 14, 10, 16, 17, 18, 19, 20, 15, 22, 23, 24, 25, 26, 27, 21, 29, 30, 31, 32, 33, 34, 35, 28, 37, 38, 39, 40, 41, 42, 43, 44, 36, 46, 47, 48, 49, 50, 51, 52, 53, 54, 45, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 55, 67
Offset: 0

Views

Author

Gus Wiseman, Mar 29 2022

Keywords

Examples

			The a(2) = 2 through a(8) = 8 compositions:
  (2)    (3)  (4)      (5)      (6)    (7)        (8)
  (1,1)       (1,3)    (1,4)    (1,5)  (1,6)      (1,7)
              (2,2)    (3,2)    (4,2)  (5,2)      (6,2)
              (1,2,1)  (1,1,3)         (1,2,4)    (1,2,5)
                       (1,2,2)         (1,3,3)    (1,4,3)
                                       (2,2,3)    (3,2,3)
                                       (1,2,3,1)  (1,2,1,4)
                                                  (1,2,3,2)
		

Crossrefs

Compositions with no nonfixed points are counted by A010054.
The version for weak excedances is A177510.
Compositions with no fixed points are counted by A238351.
The version for fixed points is A240736.
This is column k = 1 of A352523.
A011782 counts compositions.
A238349 counts compositions by fixed points, rank stat A352512.
A352486 gives the nonfixed points of A122111, counted by A330644.
A352513 counts nonfixed points in standard compositions.

Programs

  • Mathematica
    pnq[y_]:=Length[Select[Range[Length[y]],#!=y[[#]]&]];
    Table[Length[Select[Join@@Permutations/@IntegerPartitions[n],pnq[#]==1&]],{n,0,15}]

Extensions

More terms from Alois P. Heinz, Mar 30 2022

A352832 Number of reversed integer partitions y of n with exactly one fixed point y(i) = i.

Original entry on oeis.org

0, 1, 1, 1, 4, 3, 7, 7, 14, 19, 24, 32, 46, 60, 85, 109, 140, 179, 239, 300, 397, 495, 636, 790, 995, 1239, 1547, 1926, 2396, 2942, 3643, 4432, 5435, 6602, 8038, 9752, 11842, 14292, 17261, 20714, 24884, 29733, 35576, 42375, 50522, 60061, 71363, 84551, 100101
Offset: 0

Views

Author

Gus Wiseman, Apr 08 2022

Keywords

Comments

A reversed integer partition of n is a finite weakly increasing sequence of positive integers summing to n.

Examples

			The a(0) = 0 through a(8) = 14 partitions (empty column indicated by dot):
  .  (1)  (11)  (111)  (13)    (14)     (15)      (16)       (17)
                       (22)    (1112)   (114)     (115)      (116)
                       (112)   (11111)  (222)     (1123)     (134)
                       (1111)           (1113)    (11113)    (224)
                                        (1122)    (11122)    (233)
                                        (11112)   (111112)   (1115)
                                        (111111)  (1111111)  (2222)
                                                             (11114)
                                                             (11123)
                                                             (11222)
                                                             (111113)
                                                             (111122)
                                                             (1111112)
                                                             (11111111)
For example, the reversed partition (2,2,4) has a unique fixed point at the second position.
		

Crossrefs

* = unproved
*The non-reverse version is A001522, ranked by A352827, strict A352829.
*The non-reverse complement is A064428, ranked by A352826, strict A352828.
This is column k = 1 of A238352.
For no fixed point: counted by A238394, ranked by A352830, strict A025147.
For > 0 fixed points: counted by A238395, ranked by A352872, strict A096765.
The version for compositions is A240736, complement A352520.
These partitions are ranked by A352831.
A000700 counts self-conjugate partitions, ranked by A088902.
A008290 counts permutations by fixed points, nonfixed A098825.
A115720 and A115994 count partitions by their Durfee square.
A238349 counts compositions by fixed points, complement A352523.
A352822 counts fixed points of prime indices.
A352833 counts partitions by fixed points.

Programs

  • Mathematica
    pq[y_]:=Length[Select[Range[Length[y]],#==y[[#]]&]];
    Table[Length[Select[Reverse/@IntegerPartitions[n],pq[#]==1&]],{n,0,30}]

A164863 Number of ways of placing n labeled balls into 9 indistinguishable boxes; word structures of length n using a 9-ary alphabet.

Original entry on oeis.org

1, 1, 2, 5, 15, 52, 203, 877, 4140, 21147, 115974, 678514, 4211825, 27602602, 190077045, 1368705291, 10254521370, 79527284317, 635182667816, 5199414528808, 43426867585575, 368654643520692, 3170300933550687, 27542984610086665, 241205285284001240
Offset: 0

Views

Author

Alois P. Heinz, Aug 28 2009

Keywords

Crossrefs

Programs

  • Maple
    # first program:
    a:= n-> ceil(103/560*2^n +53/864*3^n +11/720*4^n +5^n/320 +6^n/2160 +7^n/10080 +9^n/362880): seq(a(n), n=0..25);
    # second program:
    a:= n-> add(Stirling2(n, k), k=0..9): seq(a(n), n=0..25);
  • Mathematica
    Table[Sum[StirlingS2[n, k], {k, 0, 9}], {n, 0, 30}] (* Robert A. Russell, Apr 25 2018 *)

Formula

a(n) = Sum_{k=0..9} stirling2 (n,k).
a(n) = ceiling (103/560*2^n +53/864*3^n +11/720*4^n +5^n/320 +6^n/2160 +7^n/10080 +9^n/362880).
G.f.: (16687*x^8 -67113*x^7 +88620*x^6 -56993*x^5 +20529*x^4 -4353*x^3 +539*x^2 -36*x+1) / ((9*x-1) *(7*x-1) *(6*x-1) *(5*x-1) *(4*x-1) *(3*x-1) *(2*x-1) *(x-1)).
G.f.: Sum_{j=0..k} A248925(k,j)*x^j / Product_{j=1..k} 1-j*x with k=9. - Robert A. Russell, Apr 25 2018

A094791 Triangle read by rows giving coefficients of polynomials arising in successive differences of (n!)_{n>=0}.

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 3, 5, 2, 1, 6, 17, 20, 9, 1, 10, 45, 100, 109, 44, 1, 15, 100, 355, 694, 689, 265, 1, 21, 196, 1015, 3094, 5453, 5053, 1854, 1, 28, 350, 2492, 10899, 29596, 48082, 42048, 14833, 1, 36, 582, 5460, 32403, 124908, 309602, 470328, 391641, 133496
Offset: 0

Views

Author

Benoit Cloitre, Jun 11 2004

Keywords

Comments

Let D_0(n)=n! and D_{k+1}(n)=D_{k}(n+1)-D_{k}(n), then D_{k}(n)=n!*P_{k}(n) where P_{k} is a polynomial with integer coefficients of degree k.
The horizontal reversal of this triangle arises as a binomial convolution of the derangements coefficients der(n,i) (numbers of permutations of size n with i derangements = A098825(n,i) = number of permutations of size n with n-i rencontres = A008290(n,n-i), see formula section). - Olivier Gérard, Jul 31 2011

Examples

			D_3(n) = n!*(n^3 + 3*n^2 + 5*n + 2).
D_4(n) = n!*(n^4 + 6*n^3 + 17*n^2 + 20*n + 9).
Table begins:
  1
  1  0
  1  1   1
  1  3   5   2
  1  6  17  20    9
  1 10  45 100  109   44
  1 15 100 355  694  689  265
  ...
		

Crossrefs

Successive differences of factorial numbers: A001563, A001564, A001565, A001688, A001689, A023043.
Rencontres numbers A008290. Partial derangements A098825.
Row sum is A000255. Signed version in A126353.

Programs

  • Maple
    with(LREtools): A094791_row := proc(n)
    delta(x!,x,n); simplify(%/x!); seq(coeff(%,x,n-j),j=0..n) end:
    seq(print(A094791_row(n)),n=0..9); # Peter Luschny, Jan 09 2015
  • Mathematica
    d[0][n_] := n!; d[k_][n_] := d[k][n] = d[k - 1][n + 1] - d[k - 1][n] // FullSimplify;
    row[k_] := d[k][n]/n! // FullSimplify // CoefficientList[#, n]& // Reverse;
    Array[row, 10, 0] // Flatten (* Jean-François Alcover, Aug 02 2019 *)

Formula

T(n, n) = A000166(n).
T(2, k) = A000217(k).
Sum_{k=0..n} T(n,n-k)*x^k = Sum_{i=0..n} der(n,i)*binomial( n+x, i) (an analog of Worpitzky's identity). - Olivier Gérard, Jul 31 2011

Extensions

Edited and T(0,0) corrected according to the author's definition by Olivier Gérard, Jul 31 2011

A284989 Triangle T(n,k) read by rows: the number of n X n {0,1} matrices with trace k where each row sum and each column sum is 2.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 0, 3, 2, 9, 24, 24, 24, 9, 216, 540, 610, 420, 210, 44, 7570, 18000, 20175, 13720, 6300, 1920, 265, 357435, 829920, 909741, 617610, 284235, 91140, 19005, 1854, 22040361, 50223600, 54295528, 36663312, 17072790, 5679184, 1337280, 203952, 14833
Offset: 0

Views

Author

R. J. Mathar, Apr 07 2017

Keywords

Examples

			0:         1
1:         0        0
2:         0        0        1
3:         1        0        3        2
4:         9       24       24       24        9
5:       216      540      610      420      210      44
6:      7570    18000    20175    13720     6300    1920     265
7:    357435   829920   909741   617610   284235   91140   19005   1854
8:  22040361 50223600 54295528 36663312 17072790 5679184 1337280 203952 14833
		

Crossrefs

Cf. A001499 (row sums), A000166 (diagonal), A007107 (column 0).

Programs

  • PARI
    P(n, t='t) = {
      my(z=vector(n, k, eval(Str("z", k))),
         s1=sum(k=1, #z, z[k]), s2=sum(k=1, #z, z[k]^2), s12=(s1^2 - s2)/2,
         f=vector(n, k, t*(s12 - z[k]*(s1 - z[k])) + z[k]*(s1 - z[k])), g=1);
      for (i=1, n, g *= f[i]; for(j=1, n, g=substpol(g, z[j]^3, 0)));
      for (k=1, n, g=polcoef(g, 2, z[k]));
      g;
    };
    seq(N) = concat([[1], [0, 0], [0, 0, 1]], apply(n->Vec(P(n)), [3..N]));
    concat(seq(8)) \\ Gheorghe Coserea, Dec 21 2018

Formula

Let z1..zn be n variables and s1 = Sum_{k=1..n} zk, s2 = Sum_{k=1..n} zk^2, s12 = (s1^2 - s2)/2, fk = t*(s12 - zk*(s1 - zk)) + zk*(s1 - zk) for k=1..n, P_n(t) = [(z1..zn)^2] Product_{k=1..n} fk. Then P_n(t) = Sum_{k=0..n} T(n,k)*t^(n-k), n >= 3. - Gheorghe Coserea, Dec 21 2018
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