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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A213652 9-nomial coefficient array: Coefficients of the polynomial (1+...+X^8)^n, n=0,1,...

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 3, 2, 1, 1, 3, 6, 10, 15, 21, 28, 36, 45, 52, 57, 60, 61, 60, 57, 52, 45, 36, 28, 21, 15, 10, 6, 3, 1, 1, 4, 10, 20, 35, 56, 84, 120, 165, 216, 270, 324, 375, 420, 456, 480, 489, 480, 456
Offset: 0

Views

Author

M. F. Hasler, Jun 17 2012

Keywords

Comments

The n-th row also yields the number of ways to get a total of n, n+1,..., 9n, when summing n integers ranging from 1 to 9.
The row sums equal 9^n = A001019(n).
The row lengths are 1+8n = A017077(n).

Examples

			The triangle starts:
(row n=0) 1; (row sum = 1, row length = 1)
(row n=1) 1,1,1,1,1,1,1,1,1; (row sum = 9, row length = 9)
(row n=2) 1,2,3,4,5,6,7,8,9,8,7,6,5,4,3,2,1; (sum = 81, length = 17)
(row n=3) 1,3,6,10,15,21,28,36,45,52,57,60,61,60,... (sum = 729, length = 25)
(row n=4) 1, 4, 10, 20, 35, 56, 84, 120, 165, 216, 270, 324, 375, 420, 456,... (sum = 9^4; length = 33),
etc.
		

Crossrefs

The q-nomial arrays are for q=2..10: A007318 (Pascal), A027907, A008287, A035343, A063260, A063265, A171890, A213652, A213651.

Programs

  • Maple
    #Define the r-nomial coefficients for r = 1, 2, 3, ...
    rnomial := (r,n,k) -> add((-1)^i*binomial(n,i)*binomial(n+k-1-r*i,n-1), i = 0..floor(k/r)):
    #Display the 9-nomials as a table
    r := 9:  rows := 10:
    for n from 0 to rows do
    seq(rnomial(r,n,k), k = 0..(r-1)*n)
    end do; # Peter Bala, Sep 07 2013
  • PARI
    concat(vector(5,k,Vec(sum(j=0,8,x^j)^(k-1))))

Formula

T(n,k) = Sum_{i=0..floor(k/9)} (-1)^i*binomial(n,i)*binomial(n+k-1-9*i,n-1) for n >= 0 and 0 <= k <= 8*n. - Peter Bala, Sep 07 2013

A267370 Partial sums of A140091.

Original entry on oeis.org

0, 6, 21, 48, 90, 150, 231, 336, 468, 630, 825, 1056, 1326, 1638, 1995, 2400, 2856, 3366, 3933, 4560, 5250, 6006, 6831, 7728, 8700, 9750, 10881, 12096, 13398, 14790, 16275, 17856, 19536, 21318, 23205, 25200, 27306, 29526, 31863, 34320, 36900, 39606, 42441, 45408, 48510
Offset: 0

Views

Author

Bruno Berselli, Jan 13 2016

Keywords

Comments

After 0, this sequence is the third column of the array in A185874.
Sequence is related to A051744 by A051744(n) = n*a(n)/3 - Sum_{i=0..n-1} a(i) for n>0.

Examples

			The sequence is also provided by the row sums of the following triangle (see the fourth formula above):
.  0;
.  1,  5;
.  4,  7, 10;
.  9, 11, 13, 15;
. 16, 17, 18, 19, 20;
. 25, 25, 25, 25, 25, 25;
. 36, 35, 34, 33, 32, 31, 30;
. 49, 47, 45, 43, 41, 39, 37, 35;
. 64, 61, 58, 55, 52, 49, 46, 43, 40;
. 81, 77, 73, 69, 65, 61, 57, 53, 49, 45, etc.
First column is A000290.
Second column is A027690.
Third column is included in A189834.
Main diagonal is A008587; other parallel diagonals: A016921, A017029, A017077, A017245, etc.
Diagonal 1, 11, 25, 43, 65, 91, 121, ... is A161532.
		

Crossrefs

Cf. similar sequences of the type n*(n+1)*(n+k)/2: A002411 (k=0), A006002 (k=1), A027480 (k=2), A077414 (k=3, with offset 1), A212343 (k=4, without the initial 0), this sequence (k=5).

Programs

  • Magma
    [n*(n+1)*(n+5)/2: n in [0..50]];
  • Mathematica
    Table[n (n + 1) (n + 5)/2, {n, 0, 50}]
    LinearRecurrence[{4,-6,4,-1},{0,6,21,48},50] (* Harvey P. Dale, Jul 18 2019 *)
  • PARI
    vector(50, n, n--; n*(n+1)*(n+5)/2)
    
  • Sage
    [n*(n+1)*(n+5)/2 for n in (0..50)]
    

Formula

O.g.f.: 3*x*(2 - x)/(1 - x)^4.
E.g.f.: x*(12 + 9*x + x^2)*exp(x)/2.
a(n) = n*(n + 1)*(n + 5)/2.
a(n) = Sum_{i=0..n} n*(n - i) + 5*i, that is: a(n) = A002411(n) + A028895(n). More generally, Sum_{i=0..n} n*(n - i) + k*i = n*(n + 1)*(n + k)/2.
a(n) = 3*A005581(n+1).
a(n+1) - 3*a(n) + 3*a(n-1) = 3*A105163(n) for n>0.
From Amiram Eldar, Jan 06 2021: (Start)
Sum_{n>=1} 1/a(n) = 163/600.
Sum_{n>=1} (-1)^(n+1)/a(n) = 4*log(2)/5 - 253/600. (End)

A277090 Expansion of Product_{k>=0} 1/(1 - x^(8*k+1)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 4, 4, 4, 4, 4, 4, 4, 5, 6, 7, 7, 7, 7, 7, 7, 8, 10, 11, 12, 12, 12, 12, 12, 13, 15, 17, 18, 19, 19, 19, 19, 20, 23, 26, 28, 29, 30, 30, 30, 31, 34, 38, 41, 43, 44, 45, 45, 46, 50, 55, 60, 63, 65, 66, 67, 68, 72, 79, 85, 90, 93, 95, 96, 98, 103, 111, 120, 127, 132, 135, 137, 139, 145
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 29 2016

Keywords

Comments

Number of partitions of n into parts congruent to 1 mod 8.
More generally, the ordinary generating function for the number of partitions of n into parts congruent to 1 mod m (for m>0) is Product_{k>=0} 1/(1 - x^(m*k+1)).

Examples

			a(10) = 2, because we have [9, 1] and [1, 1, 1, 1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Cf. similar sequences of number of partitions of n into parts congruent to 1 mod m: A000009 (m=2), A035382 (m=3), A035451 (m=4), A109697 (m=5), A109701 (m=6), A109703 (m=7).

Programs

  • Mathematica
    CoefficientList[Series[QPochhammer[x, x^8]^(-1), {x, 0, 90}], x]

Formula

G.f.: Product_{k>=0} 1/(1 - x^(8*k+1)).
a(n) ~ exp((Pi*sqrt(n))/(2*sqrt(3)))*Gamma(1/8)/(4*3^(1/16)*(2*Pi)^(7/8)*n^(9/16)).
a(n) = (1/n)*Sum_{k=1..n} A284100(k)*a(n-k), a(0) = 1. - Seiichi Manyama, Mar 20 2017

A004768 Binary expansion ends 001.

Original entry on oeis.org

9, 17, 25, 33, 41, 49, 57, 65, 73, 81, 89, 97, 105, 113, 121, 129, 137, 145, 153, 161, 169, 177, 185, 193, 201, 209, 217, 225, 233, 241, 249, 257, 265, 273, 281, 289, 297, 305, 313, 321, 329, 337, 345, 353, 361, 369, 377, 385, 393, 401, 409, 417, 425, 433, 441, 449, 457, 465, 473, 481, 489
Offset: 0

Views

Author

Keywords

Comments

Apart from initial term(s), dimension of the space of weight 2n cusp forms for Gamma_0( 28 ).

Crossrefs

Complement of A004774.
Cf. A017077.
Cf. A146302. - Reinhard Zumkeller, Oct 30 2008

Programs

  • Magma
    [8*n + 9: n in [0..60]]; // Vincenzo Librandi, Jul 11 2011
    
  • Mathematica
    Rest[FromDigits[#,2]&/@(Join[#,{0,0,1}]&/@Tuples[{0,1},7])] (* or *) LinearRecurrence[{2,-1},{9,17},100] (* Harvey P. Dale, May 10 2015 *)
  • PARI
    a(n) = 8*n+9 \\ Charles R Greathouse IV, Sep 24 2012
    
  • PARI
    Vec((9 - x) / (1 - x)^2 + O(x^50)) \\ Colin Barker, Jul 04 2019
    
  • Python
    def a(n): return 8*n + 9
    print([a(n) for n in range(61)]) # Michael S. Branicky, Sep 17 2021

Formula

From Reinhard Zumkeller, Oct 30 2008: (Start)
a(n) = 8*n + 9.
For n > 0: a(n) = A017077(n-1). (End)
a(n) = 2*a(n-1) - a(n-2); a(0)=9, a(1)=17. - Harvey P. Dale, May 10 2015
G.f.: (9 - x) / (1 - x)^2. - Colin Barker, Jul 04 2019
E.g.f.: exp(x)*(9 + 8*x). - Stefano Spezia, May 13 2021

A371095 Array A read by upward antidiagonals in which the entry A(n,k) in row n and column k is defined by A(1, k) = 8*k-7, and A(n+1, k) = R(A(n, k)), n,k >= 1, where Reduced Collatz function R(n) gives the odd part of 3n+1.

Original entry on oeis.org

1, 1, 9, 1, 7, 17, 1, 11, 13, 25, 1, 17, 5, 19, 33, 1, 13, 1, 29, 25, 41, 1, 5, 1, 11, 19, 31, 49, 1, 1, 1, 17, 29, 47, 37, 57, 1, 1, 1, 13, 11, 71, 7, 43, 65, 1, 1, 1, 5, 17, 107, 11, 65, 49, 73, 1, 1, 1, 1, 13, 161, 17, 49, 37, 55, 81, 1, 1, 1, 1, 5, 121, 13, 37, 7, 83, 61, 89, 1, 1, 1, 1, 1, 91, 5, 7, 11, 125, 23, 67, 97
Offset: 1

Views

Author

Antti Karttunen, Apr 24 2024

Keywords

Examples

			Array begins:
n\k|  1   2   3   4   5    6   7   8   9   10  11   12   13   14   15   16
---+------------------------------------------------------------------------
1  |  1,  9, 17, 25, 33,  41, 49, 57, 65,  73, 81,  89,  97, 105, 113, 121,
2  |  1,  7, 13, 19, 25,  31, 37, 43, 49,  55, 61,  67,  73,  79,  85,  91,
3  |  1, 11,  5, 29, 19,  47,  7, 65, 37,  83, 23, 101,  55, 119,   1, 137,
4  |  1, 17,  1, 11, 29,  71, 11, 49,  7, 125, 35,  19,  83, 179,   1, 103,
5  |  1, 13,  1, 17, 11, 107, 17, 37, 11,  47, 53,  29, 125, 269,   1, 155,
6  |  1,  5,  1, 13, 17, 161, 13,  7, 17,  71,  5,  11,  47, 101,   1, 233,
7  |  1,  1,  1,  5, 13, 121,  5, 11, 13, 107,  1,  17,  71,  19,   1, 175,
8  |  1,  1,  1,  1,  5,  91,  1, 17,  5, 161,  1,  13, 107,  29,   1, 263,
9  |  1,  1,  1,  1,  1, 137,  1, 13,  1, 121,  1,   5, 161,  11,   1, 395,
10 |  1,  1,  1,  1,  1, 103,  1,  5,  1,  91,  1,   1, 121,  17,   1, 593,
11 |  1,  1,  1,  1,  1, 155,  1,  1,  1, 137,  1,   1,  91,  13,   1, 445,
12 |  1,  1,  1,  1,  1, 233,  1,  1,  1, 103,  1,   1, 137,   5,   1, 167,
13 |  1,  1,  1,  1,  1, 175,  1,  1,  1, 155,  1,   1, 103,   1,   1, 251,
14 |  1,  1,  1,  1,  1, 263,  1,  1,  1, 233,  1,   1, 155,   1,   1, 377,
15 |  1,  1,  1,  1,  1, 395,  1,  1,  1, 175,  1,   1, 233,   1,   1, 283,
16 |  1,  1,  1,  1,  1, 593,  1,  1,  1, 263,  1,   1, 175,   1,   1, 425,
		

Crossrefs

Cf. A017077 (row 1), A016921 (row 2), A075677.
Cf. also A371096, A371097.

Programs

  • PARI
    up_to = 91;
    R(n) = { n = 1+3*n; n>>valuation(n, 2); };
    A371095sq(n,k) = if(1==n,8*k-7,R(A371095sq(n-1,k)));
    A371095list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A371095sq((a-(col-1)),col))); (v); };
    v371095 = A371095list(up_to);
    A371095(n) = v371095[n];

A028993 Odd 10-gonal (or decagonal) numbers.

Original entry on oeis.org

1, 27, 85, 175, 297, 451, 637, 855, 1105, 1387, 1701, 2047, 2425, 2835, 3277, 3751, 4257, 4795, 5365, 5967, 6601, 7267, 7965, 8695, 9457, 10251, 11077, 11935, 12825, 13747, 14701, 15687, 16705, 17755, 18837, 19951, 21097, 22275, 23485, 24727, 26001, 27307, 28645
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

Formula

a(n) = (2*n+1)*(8*n+1). - N. J. A. Sloane
G.f.: -(7*x^2+24*x+1)/(x-1)^3. - Colin Barker, Nov 18 2012
Sum_{n>=0} 1/a(n) = (4*log(2) + (sqrt(2)+1)*Pi + 2*sqrt(2)*log(1+sqrt(2)))/12. - Amiram Eldar, Feb 27 2022
From Elmo R. Oliveira, Oct 27 2024: (Start)
E.g.f.: exp(x)*(1 + 26*x + 16*x^2).
a(n) = A005408(n)*A017077(n) = A001107(2*n+1).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2. (End)

A139617 a(n) = 136*n + 17.

Original entry on oeis.org

17, 153, 289, 425, 561, 697, 833, 969, 1105, 1241, 1377, 1513, 1649, 1785, 1921, 2057, 2193, 2329, 2465, 2601, 2737, 2873, 3009, 3145, 3281, 3417, 3553, 3689, 3825, 3961, 4097, 4233, 4369, 4505, 4641, 4777, 4913, 5049, 5185, 5321
Offset: 0

Views

Author

Omar E. Pol, May 21 2008

Keywords

Comments

Numbers of the 17th column of positive numbers in the square array of nonnegative and polygonal numbers A139600. Also, numbers of the 17th column in the square array A057145.

Crossrefs

Programs

Formula

From Elmo R. Oliveira, Apr 04 2024: (Start)
G.f.: 17*(1+7*x)/(x-1)^2.
E.g.f.: 17*exp(x)*(1 + 8*x).
a(n) = 17*A017077(n).
a(n) = 2*a(n-1) - a(n-2) for n >= 2. (End)

A238303 Triangle T(n,k), 0<=k<=n, read by rows given by T(n,0) = 1, T(n,k) = 2 if k>0.

Original entry on oeis.org

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

Views

Author

Philippe Deléham, Feb 24 2014

Keywords

Comments

Row sums are A005408(n).
Diagonals sums are A109613(n).
Sum_{k=0..n} T(n,k)*x^k = A033999(n), A000012(n), A005408(n), A036563(n+2), A058481(n+1), A083584(n), A137410(n), A233325(n), A233326(n), A233328(n), A211866(n+1), A165402(n+1) for x = -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 respectively.
Sum_{k=0..n} T(n,k)*x^(n-k) = A151575(n), A000012(n), A040000(n), A005408(n), A033484(n), A048473(n), A020989(n), A057651(n), A061801(n), A238275(n), A238276(n), A138894(n), A090843(n), A199023(n) for x = -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 respectively.
Sum_{k=0..n} T(n,k)^x = A000027(n+1), A005408(n), A016813(n), A017077(n) for x = 0, 1, 2, 3 respectively.
Sum_{k=0..n} k*T(n,k) = A002378(n).
Sum_{k=0..n} A000045(k)*T(n,k) = A019274(n+2).
Sum_{k=0..n} A000142(k)*T(n,k) = A066237(n+1).

Examples

			Triangle begins:
1;
1, 2;
1, 2, 2;
1, 2, 2, 2;
1, 2, 2, 2, 2;
1, 2, 2, 2, 2, 2;
1, 2, 2, 2, 2, 2, 2;
1, 2, 2, 2, 2, 2, 2, 2;
1, 2, 2, 2, 2, 2, 2, 2, 2;
1, 2, 2, 2, 2, 2, 2, 2, 2, 2;
1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2;
1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2;
...
		

Crossrefs

Cf. Diagonals: A040000.
Cf. Columns: A000012, A007395.
First differences of A001614.

Programs

Formula

T(n,0) = A000012(n) = 1, T(n+k,k) = A007395(n) = 2 for k>0.

Extensions

Data section extended to a(104) by Antti Karttunen, Jan 19 2025

A238477 a(n) = 32*n - 27 for n >= 1. Second column of triangle A238475.

Original entry on oeis.org

5, 37, 69, 101, 133, 165, 197, 229, 261, 293, 325, 357, 389, 421, 453, 485, 517, 549, 581, 613, 645, 677, 709, 741, 773, 805, 837, 869, 901, 933, 965, 997, 1029, 1061, 1093, 1125, 1157, 1189, 1221, 1253, 1285, 1317, 1349, 1381, 1413, 1445, 1477, 1509, 1541, 1573
Offset: 1

Views

Author

Wolfdieter Lang, Mar 10 2014

Keywords

Comments

This sequence gives all start numbers a(n) (sorted increasingly) of Collatz sequences of length 6 following the pattern udddd = ud^4, with u (for 'up'), mapping an odd number m to 3*m+1, and d (for 'down'), mapping an even number m to m/2. The last entry of this sequence is required to be odd and it is given by 6*n - 5.
This appears in Example 2.1. for x = 4 in the M. Trümper paper given as a link below.

Examples

			a(1) = 5 because the Collatz sequence of length 6 is [5, 16, 8, 4, 2, 1], following the pattern udddd, ending in 1, and 5 is the smallest start number following this pattern ending in an odd number.
a(2) = 37 with the length 6 Collatz sequence [37, 112, 56, 28, 14, 7] ending in 12 - 5 = 7, and this is the second smallest start number with this sequence pattern ending in an odd number.
		

Crossrefs

Cf. A017077 (first column), A238475, A239123 (third column).

Programs

  • Mathematica
    CoefficientList[Series[(5 + 27 x)/(1 - x)^2, {x, 0, 50}], x] (* Vincenzo Librandi, Mar 12 2014 *)

Formula

O.g.f.: x*(5+27*x)/(1-x)^2.
From Elmo R. Oliveira, Apr 04 2025: (Start)
E.g.f.: 27 + exp(x)*(32*x - 27).
a(n) = 2*a(n-1) - a(n-2) for n > 2. (End)

A326296 Triangle of numbers T(n,k) = 2*floor(k/2)*(n-k) + ceiling((k-1)^2/2), 1<=k<=n.

Original entry on oeis.org

0, 0, 1, 0, 3, 2, 0, 5, 4, 5, 0, 7, 6, 9, 8, 0, 9, 8, 13, 12, 13, 0, 11, 10, 17, 16, 19, 18, 0, 13, 12, 21, 20, 25, 24, 25, 0, 15, 14, 25, 24, 31, 30, 33, 32, 0, 17, 16, 29, 28, 37, 36, 41, 40, 41, 0, 19, 18, 33, 32, 43, 42, 49, 48, 51, 50, 0, 21, 20, 37, 36, 49, 48, 57, 56, 61, 60, 61
Offset: 1

Views

Author

M. Ryan Julian Jr., Sep 10 2019

Keywords

Comments

T(n,k) gives the maximum number of inversions in a permutation on n symbols containing a single k-cycle and (n-k) other fixed points.
T(n,n) = A000982(n).
T(n,n-1) = A097063(n).

Examples

			Triangle begins:
0;
0, 1;
0, 3, 2;
0, 5, 4, 5;
0, 7, 6, 9, 8;
0, 9, 8, 13, 12, 13;
0, 11, 10, 17, 16, 19, 18;
0, 13, 12, 21, 20, 25, 24, 25;
0, 15, 14, 25, 24, 31, 30, 33, 32;
0, 17, 16, 29, 28, 37, 36, 41, 40, 41;
0, 19, 18, 33, 32, 43, 42, 49, 48, 51, 50;
0, 21, 20, 37, 36, 49, 48, 57, 56, 61, 60, 61;
...
		

Crossrefs

Diagonals give A000982, A097063, A326657, A326658.
Row sums give A000330.

Programs

  • PARI
    T(n,k) = {2*floor(k/2)*(n-k) + ceil((k-1)^2/2)} \\ Andrew Howroyd, Sep 10 2019

Formula

T(n,k) = 2*floor(k/2)*(n-k) + ceiling((k-1)^2/2).
T(n,k) = 2*floor(k/2)*(n-k) + binomial(k,2) - ceiling(k/2) + 1.
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