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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A072720 Number of partitions of n into parts which are each powers of a single number (which may vary between partitions).

Original entry on oeis.org

1, 1, 2, 3, 5, 6, 10, 11, 15, 17, 23, 24, 34, 35, 43, 47, 57, 58, 73, 74, 91, 96, 112, 113, 139, 141, 163, 168, 197, 198, 235, 236, 272, 279, 317, 321, 378, 379, 427, 436, 501, 502, 575, 576, 653, 666, 742, 743, 851, 853, 952, 963, 1080, 1081, 1211, 1216, 1361
Offset: 0

Views

Author

Henry Bottomley, Jul 05 2002

Keywords

Comments

First differs from A322912 at a(12) = 34, A322912(12) = 33.

Examples

			a(6)=10 since 6 can be written as 6 (powers of 6), 5+1 (5), 4+1+1 (4 or 2), 3+3 (3), 3+1+1+1 (3), 4+2 (2), 2+2+2 (2), 2+2+1+1 (2), 2+1+1+1+1 (2) and 1+1+1+1+1+1 (powers of anything).
From _Gus Wiseman_, Jan 01 2019: (Start)
The a(1) = 1 through a(8) = 15 integer partitions:
  (1)  (2)   (3)    (4)     (5)      (6)       (7)        (8)
       (11)  (21)   (22)    (41)     (33)      (61)       (44)
             (111)  (31)    (221)    (42)      (331)      (71)
                    (211)   (311)    (51)      (421)      (422)
                    (1111)  (2111)   (222)     (511)      (611)
                            (11111)  (411)     (2221)     (2222)
                                     (2211)    (4111)     (3311)
                                     (3111)    (22111)    (4211)
                                     (21111)   (31111)    (5111)
                                     (111111)  (211111)   (22211)
                                               (1111111)  (41111)
                                                          (221111)
                                                          (311111)
                                                          (2111111)
                                                          (11111111)
(End)
		

Crossrefs

Programs

  • Mathematica
    radbase[n_]:=n^(1/GCD@@FactorInteger[n][[All,2]]);
    Table[Length[Select[IntegerPartitions[n],SameQ@@radbase/@DeleteCases[#,1]&]],{n,30}] (* Gus Wiseman, Jan 01 2019 *)

Formula

a(n) = a(n-1) + A072721(n). a(p) = a(p-1)+1 for p prime.

A292477 Square array A(n,k), n >= 0, k >= 2, read by antidiagonals: A(n,k) = [x^(k*n)] Product_{j>=0} 1/(1 - x^(k^j)).

Original entry on oeis.org

1, 1, 2, 1, 2, 4, 1, 2, 3, 6, 1, 2, 3, 5, 10, 1, 2, 3, 4, 7, 14, 1, 2, 3, 4, 6, 9, 20, 1, 2, 3, 4, 5, 8, 12, 26, 1, 2, 3, 4, 5, 7, 10, 15, 36, 1, 2, 3, 4, 5, 6, 9, 12, 18, 46, 1, 2, 3, 4, 5, 6, 8, 11, 15, 23, 60, 1, 2, 3, 4, 5, 6, 7, 10, 13, 18, 28, 74, 1, 2, 3, 4, 5, 6, 7, 9, 12, 15, 21, 33, 94
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 17 2017

Keywords

Comments

A(n,k) is the number of partitions of k*n into powers of k.

Examples

			Square array begins:
   1,  1,  1,  1,  1,  1, ...
   2,  2,  2,  2,  2,  2, ...
   4,  3,  3,  3,  3,  3, ...
   6,  5,  4,  4,  4,  4, ...
  10,  7,  6,  5,  5,  5, ...
  14,  9,  8,  7,  6,  6, ...
		

Crossrefs

Columns k=2..5 give A000123, A005704, A005705, A005706.
Mirror of A089688 (excluding the first row).

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[Product[1/(1 - x^k^i), {i, 0, n}], {x, 0, k n}]][j - n + 2], {j, 0, 12}, {n, 0, j}] // Flatten

A309677 G.f. A(x) satisfies: A(x) = A(x^3) / (1 - x)^2.

Original entry on oeis.org

1, 2, 3, 6, 9, 12, 18, 24, 30, 42, 54, 66, 87, 108, 129, 162, 195, 228, 279, 330, 381, 456, 531, 606, 711, 816, 921, 1068, 1215, 1362, 1563, 1764, 1965, 2232, 2499, 2766, 3120, 3474, 3828, 4290, 4752, 5214, 5805, 6396, 6987, 7740, 8493, 9246, 10194, 11142
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 12 2019

Keywords

Comments

Self-convolution of A062051.

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<0, 0,
          b(n, i-1)+(p-> `if`(p>n, 0, b(n-p, i)))(3^i)))
        end:
    a:= n-> add(b(j, ilog[3](j))*b(n-j, ilog[3](n-j)), j=0..n):
    seq(a(n), n=0..52);  # Alois P. Heinz, Aug 12 2019
  • Mathematica
    nmax = 52; A[] = 1; Do[A[x] = A[x^3]/(1 - x)^2 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    nmax = 52; CoefficientList[Series[Product[1/(1 - x^(3^k))^2, {k, 0, Floor[Log[3, nmax]] + 1}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=0} 1/(1 - x^(3^k))^2.

A371709 Expansion of g.f. A(x) satisfying A( x*A(x)^2 + x*A(x)^3 ) = A(x)^3.

Original entry on oeis.org

1, 1, 1, 2, 6, 16, 39, 99, 271, 764, 2157, 6128, 17658, 51534, 151635, 448962, 1337493, 4008040, 12072594, 36524898, 110943633, 338218626, 1034509917, 3173811240, 9763898994, 30113782641, 93094164244, 288415278638, 895332445053, 2784580242557, 8675408291598, 27072326322939
Offset: 1

Views

Author

Paul D. Hanna, May 02 2024

Keywords

Comments

Compare to the following identities of the Catalan function C(x) = x + C(x)^2 (A000108):
(1) C(x)^2 = C( x*C(x)*(1 + C(x)) ),
(2) C(x)^4 = C( x*C(x)^3*(1 + C(x))*(1 + C(x)^2) ),
(3) C(x)^8 = C( x*C(x)^7*(1 + C(x))*(1 + C(x)^2)*(1 + C(x)^4) ),
(4) C(x)^(2^n) = C( x*C(x)^(2^n-1)*Product_{k=0..n-1} (1 + C(x)^(2^k)) ) for n > 0.
a(3^n) == 1 (mod 3) for n >= 0.
a(2*3^n) == 1 (mod 3) for n >= 0.
a(n) == 2 (mod 3) iff n is the sum of 2 distinct powers of 3 (A038464).

Examples

			G.f. A(x) = x + x^2 + x^3 + 2*x^4 + 6*x^5 + 16*x^6 + 39*x^7 + 99*x^8 + 271*x^9 + 764*x^10 + 2157*x^11 + 6128*x^12 + 17658*x^13 + 51534*x^14 + 151635*x^15 + 448962*x^16 + ...
where A( x*A(x)^2*(1 + A(x)) ) = A(x)^3.
RELATED SERIES.
A(x)^2 = x^2 + 2*x^3 + 3*x^4 + 6*x^5 + 17*x^6 + 48*x^7 + 126*x^8 + 332*x^9 + 918*x^10 + 2616*x^11 + 7504*x^12 + ...
A(x)^3 = x^3 + 3*x^4 + 6*x^5 + 13*x^6 + 36*x^7 + 105*x^8 + 292*x^9 + 801*x^10 + 2256*x^11 + 6515*x^12 + 18981*x^13 + ...
A(x)^2 + A(x)^3 = x^2 + 3*x^3 + 6*x^4 + 12*x^5 + 30*x^6 + 84*x^7 + 231*x^8 + 624*x^9 + 1719*x^10 + 4872*x^11 + 14019*x^12 + 40599*x^13 + ...
Let B(x) be the series reversion of g.f. A(x), B(A(x)) = x, then
B(x) * (1+x)/(1+x^3) = x - 2*x^4 + 3*x^7 - 5*x^10 + 7*x^13 - 9*x^16 + 12*x^19 - 15*x^22 + 18*x^25 - 23*x^28 + ... + (-1)^n*A005704(n)*x^(3*n+1) + ...
where A005704 is the number of partitions of 3*n into powers of 3.
We can show that g.f. A(x) = A( x*A(x)^2*(1 + A(x)) )^(1/3) satisfies
(4) A(x) = x * Product_{n>=0} (1 + A(x)^(3^n))
by substituting x*A(x)^2*(1 + A(x)) for x in (4) to obtain
A(x)^3 = x * A(x)^2*(1 + A(x)) * Product_{n>=1} (1 + A(x)^(3^n))
which is equivalent to formula (4).
SPECIFIC VALUES.
A(3/10) = 0.526165645044542830201162330432965674027415264612114520...
A(1/4) = 0.353259384374080248921564026412797625837830114153200664...
A(1/5) = 0.255218141344695821239609680309162895225297482063273545...
A(t) = 1/2 and A(t*3/8) = 1/8 at t = (1/2)/Product_{n>=0} (1 + 1/2^(3^n)) = 0.295718718466711580562679377308518930409875701753934072...
A(t) = 1/3 and A(t*4/27) = 1/27 at t = (1/3)/Product_{n>=0} (1 + 1/3^(3^n)) = 0.241059181496179959557718992589733756750585121455883861...
A(t) = 1/4 and A(t*5/64) = 1/64 at t = (1/4)/Product_{n>=0} (1 + 1/4^(3^n)) = 0.196922325724019432212969925740117827612003158137366017...
		

Crossrefs

Programs

  • PARI
    /* Using series reversion of x/Product_{n>=0} (1 + x^(3^n)) */
    {a(n) = my(A); A = serreverse( x/prod(k=0,ceil(log(n)/log(3)), (1 + x^(3^k) +x*O(x^n)) ) ); polcoeff(A,n)}
    for(n=1,35, print1(a(n),", "))
    
  • PARI
    /* Using A(x)^3 = A( x*A(x)^2 + x*A(x)^3 ) */
    {a(n) = my(A=[1],F); for(i=1,n, A = concat(A,0); F = x*Ser(A);
    A[#A] = polcoeff( subst(F,x, x*F^2 + x*F^3 ) - F^3, #A+2) ); A[n]}
    for(n=1,35, print1(a(n),", "))

Formula

G.f. A(x) = Sum_{n>=1} a(n)*x^n satisfies the following formulas.
(1) A(x)^3 = A( x*A(x)^2*(1 + A(x)) ).
(2) A(x)^9 = A( x*A(x)^8*(1 + A(x))*(1 + A(x)^3) ).
(3) A(x)^27 = A( x*A(x)^26*(1 + A(x))*(1 + A(x)^3)*(1 + A(x)^9) ).
(4) A(x) = x * Product_{n>=0} (1 + A(x)^(3^n)).
(5) A(x) = Series_Reversion( x / Product_{n>=0} (1 + x^(3^n)) ).
a(n) ~ c * d^n / n^(3/2), where d = 3.2753449994351908157330968510747739... and c = 0.1559869008021616116037651076359... - Vaclav Kotesovec, May 03 2024
The radius of convergence r of g.f. A(x) and A(r) satisfy 1 = Sum_{n>=0} 3^n * A(r)^(3^n) / (1 + A(r)^(3^n)) and r = A(r) / Product_{n>=0} (1 + A(r)^(3^n)), where r = 0.30531134893345362211... = 1/d (d is given above) and A(r) = 0.600582105427215700175254768411726892599... - Paul D. Hanna, May 03 2024

A089649 a(1)=1, a(2)=2, a(n) = a(n-1) + a(floor((n+1)/3)).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 10, 13, 16, 19, 23, 27, 31, 37, 43, 49, 57, 65, 73, 83, 93, 103, 116, 129, 142, 158, 174, 190, 209, 228, 247, 270, 293, 316, 343, 370, 397, 428, 459, 490, 527, 564, 601, 644, 687, 730, 779, 828, 877, 934, 991, 1048, 1113, 1178, 1243, 1316, 1389
Offset: 1

Views

Author

Philippe Deléham, Jan 02 2004

Keywords

Comments

Partial sums of the sequence: a(1)=1, a(1), a(1), a(1), a(2), a(2), a(2), a(3), a(3), ... each term repeated 3 times.

Crossrefs

Programs

  • Mathematica
    Fold[Append[#1, #1[[-1]] + #1[[Quotient[#2 + 1, 3]]]] &, {1, 2}, Range[3, 57]] (* Ivan Neretin, Nov 25 2016 *)
  • PARI
    a(n)=if(n<2,1,a(n-1)+a(floor((n+1)/3)))

A183038 G.f.: exp( Sum_{n>=1} A051064(n)*3^A051064(n)*x^n/n ) where A051064(n) equals the 3-adic valuation of 3n.

Original entry on oeis.org

1, 3, 6, 15, 30, 51, 93, 156, 240, 387, 597, 870, 1311, 1920, 2697, 3873, 5448, 7422, 10278, 14016, 18636, 25098, 33402, 43548, 57333, 74757, 95820, 123780, 158637, 200391, 254778, 321798, 401451, 503490, 627915, 774726, 960156, 1184205, 1446873
Offset: 0

Views

Author

Paul D. Hanna, Dec 19 2010

Keywords

Comments

Compare to B(x), the g.f. of the number of partitions of 3n into powers of 3 (A005704):
B(x) = exp( Sum_{n>=1} 3^A051064(n)*x^n/n ) = (1-x)^(-1)*Product_{n>=0} 1/(1 - x^(3^n)).

Examples

			G.f.: A(x) =  1 + 3*x + 6*x^2 + 15*x^3 + 30*x^4 + 51*x^5 + 93*x^6 +...
log(A(x)) = 3*x + 3*x^2/2 + 18*x^3/3 + 3*x^4/4 + 3*x^5/5 + 18*x^6/6 + 3*x^7/7 + 3*x^8/8 + 81*x^9/9 + 3*x^10/10 + 3*x^11/11 + 18*x^12/12 +...
G.f. satisfies A(x) = A(x^3)*G(x) where G(x) is the g.f. of A161809:
G(x) = 1 + 3*x + 6*x^2 + 12*x^3 + 21*x^4 + 33*x^5 + 51*x^6 +...
TRISECTIONS of g.f. begin:
T_0(x) = 1 + 15*x + 93*x^2 + 387*x^3 + 1311*x^4 + 3873*x^5 +...
T_1(x) = 3 + 30*x + 156*x^2 + 597*x^3 + 1920*x^4 + 5448*x^5 +...
T_2(x) = 6 + 51*x + 240*x^2 + 870*x^3 + 2697*x^4 + 7422*x^5 +...
where the ratios involve Fibonacci numbers:
T_1(x)/T_0(x) = 3*(1 - 5*x + 34*x^2 - 233*x^3 +...+ (-1)^n*Fibonacci(4n+1)*x^n +...);
T_2(x)/T_0(x) = 3*(2 - 13*x + 89*x^2 - 610*x^3 +...+ (-1)^n*Fibonacci(4n+3)*x^n +...).
		

Crossrefs

Programs

  • PARI
    {a(n)=polcoeff(exp(sum(m=1,n,valuation(3*m,3)*3^valuation(3*m,3)*x^m/m)+x*O(x^n)),n)}

Formula

G.f. satisfies: A(x) = (1-x^3)/(1-x)^3 * A(x^3)^2/A(x^9).
G.f. satisfies: A(x) = A(x^3)*G(x) where G(x) = G(x^3)*(1+x+x^2)/(1-x)^2 is the g.f. of A161809.
Define TRISECTIONS: A(x) = T_0(x^3) + x*T_1(x^3) + x^2*T_2(x^3), then:
T_1(x)/T_0(x) = 3*(1 + 2*x)/(1 + 7*x + x^2) and
T_2(x)/T_0(x) = 3*(2 + x)/(1 + 7*x + x^2).

A268128 a(n) = (A000123(n) - A001316)/2.

Original entry on oeis.org

0, 0, 1, 1, 4, 5, 8, 9, 17, 21, 28, 33, 45, 53, 66, 75, 100, 117, 140, 161, 193, 221, 258, 291, 344, 389, 446, 499, 573, 639, 722, 797, 913, 1013, 1132, 1249, 1393, 1533, 1698, 1859, 2060, 2253, 2478, 2699, 2965, 3223, 3522, 3813, 4173, 4517, 4910, 5299, 5753
Offset: 0

Views

Author

Tom Edgar, Jan 26 2016

Keywords

Crossrefs

Programs

  • Mathematica
    b[0] = 1; b[n_] := b[n] = b[Floor[n/2]] + b[n - 1];
    c[n_] := Sum[Mod[Binomial[n, k], 2], {k, 0, n}];
    a[n_] := (b[n] - c[n])/2;
    Table[a[n], {n, 0, 52}] (* Jean-François Alcover, Dec 12 2018 *)
  • Sage
    def b(n):
        A=[1]
        for i in [1..n]:
            A.append(A[i-1] + A[floor(i/2)])
        return A[n]
    [(b(n)-prod(x+1 for x in n.digits(2)))/2 for n in [0..60]]

Formula

Let b(0) = 1 and b(n) = b(n-1) + b(floor(n/2)) and let c(n) = Product_{i=0..k}(n_i+1) where n = Sum_{i=0..k}n_i*2^i is the binary representation of n. Then a(n) = (1/2)*(b(n) - c(n)).

A294298 Sum of products of terms in all partitions of 3*n into powers of 3.

Original entry on oeis.org

1, 4, 13, 49, 157, 481, 1534, 4693, 14170, 43357, 130918, 393601, 1188454, 3573013, 10726690, 32248957, 96815758, 290516161, 872169223, 2617128409, 7852005967, 23561605318, 70690403371, 212076797530, 636280680100, 1908892327810, 5726727270940, 17180634420931
Offset: 0

Views

Author

Seiichi Manyama, Oct 27 2017

Keywords

Examples

			n | partitions of 3*n into powers of 3                          | a(n)
----------------------------------------------------------------------------------
1 | 3  , 1+1+1                                                  | 3+1        =  4.
2 | 3+3, 3+1+1+1, 1+1+1+1+1+1                                   | 9+3+1      = 13.
3 | 9  , 3+3+3  , 3+3+1+1+1  , 3+1+1+1+1+1+1, 1+1+1+1+1+1+1+1+1 | 9+27+9+3+1 = 49.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(n=0, p,
         `if`(i<1, 0, add(b(n-j*i, i/3, p*i^j), j=0..n/i)))
        end:
    a:= n-> (t-> b(t, 3^ilog[3](t), 1))(3*n):
    seq(a(n), n=0..33);  # Alois P. Heinz, Oct 27 2017
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[n == 0, p, If[i < 1, 0, Sum[b[n - j i, i/3, p i^j], {j, 0, n/i}]]];
    a[n_] := b[3n, 3^Floor@Log[3, 3n], 1];
    a /@ Range[0, 33] (* Jean-François Alcover, Nov 23 2020, after Alois P. Heinz *)

Formula

a(n) = [x^(3*n)] Product_{k>=0} 1/(1 - 3^k*x^(3^k)). - Ilya Gutkovskiy, Sep 10 2018
a(n) ~ c * 3^n, where c = 2.2530906593645919365992433370928351696108819534655299832797806149219665... - Vaclav Kotesovec, Jun 18 2019

A089688 Table T(n,k), n>=0 and k>=1, read by antidiagonals; the k-th row is defined by : partitions of k*n into powers of k (with T(0,k) = 1).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 2, 1, 1, 6, 3, 2, 1, 1, 10, 5, 3, 2, 1, 1, 14, 7, 4, 3, 2, 1, 1, 20, 9, 6, 4, 3, 2, 1, 1, 26, 12, 8, 5, 4, 3, 2, 1, 1, 36, 15, 10, 7, 5, 4, 3, 2, 1, 1, 46, 18, 12, 9, 6, 5, 4, 3, 2, 1, 1, 60, 23, 15, 11, 8, 6, 5, 4, 3, 2, 1
Offset: 0

Views

Author

Philippe Deléham, Jan 05 2004

Keywords

Examples

			Row k = 1 : 1, 1, 1, 1,  1,  1,  1,  1,  1,  1,  1,  1, ... (see A000012).
Row k = 2 : 1, 2, 4, 6, 10, 14, 20, 26, 36, 46, 60, 74, ... (see A000123).
Row k = 3 : 1, 2, 3, 5,  7,  9, 12, 15, 18, 23, 28, 33, ... (see A005704).
Row k = 4 : 1, 2, 3, 4,  6,  8, 10, 12, 15, 18, 21, 24, ... (see A005705).
Row k = 5 : 1, 2, 3, 4,  5,  7,  9, 11, 13, 15, 18, 21, ... (see A005706).
		

A306727 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals: A(n,k) is the number of partitions of 3*n into powers of 3 less than or equal to 3^k.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 3, 4, 1, 1, 2, 3, 5, 5, 1, 1, 2, 3, 5, 7, 6, 1, 1, 2, 3, 5, 7, 9, 7, 1, 1, 2, 3, 5, 7, 9, 12, 8, 1, 1, 2, 3, 5, 7, 9, 12, 15, 9, 1, 1, 2, 3, 5, 7, 9, 12, 15, 18, 10, 1, 1, 2, 3, 5, 7, 9, 12, 15, 18, 22, 11, 1, 1, 2, 3, 5, 7, 9, 12, 15, 18, 23, 26, 12, 1
Offset: 0

Views

Author

Serguei Zolotov, Mar 06 2019

Keywords

Comments

Column sequences converge to A005704.

Examples

			A(3,3) = 5, because there are 5 partitions of 3*3=9 into powers of 3 less than or equal to 3^3=9: [9], [3,3,3], [3,3,1,1,1], [3,1,1,1,1,1,1], [1,1,1,1,1,1,1,1,1].
Square array A(n,k) begins:
  1, 1, 1, 1, 1, 1,  ...
  1, 2, 2, 2, 2, 2,  ...
  1, 3, 3, 3, 3, 3,  ...
  1, 4, 5, 5, 5, 5,  ...
  1, 5, 7, 7, 7, 7,  ...
  1, 6, 9, 9, 9, 9,  ...
		

Crossrefs

Main diagonal gives A005704.
A181322 gives array for base p=2.

Programs

  • Mathematica
    nmax = 12;
    f[k_] := f[k] = 1/(1-x) 1/Product[1-x^(3^j), {j, 0, k-1}] + O[x]^(nmax+1) // CoefficientList[#, x]&;
    A[n_, k_] := f[k][[n+1]];
    Table[A[n-k, k], {n, 0, nmax}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Nov 20 2019 *)
  • Python
    def aseq(p, x, k):
        # generic algorithm for any p - power base, p=3 for this sequence
        if x < 0:
            return 0
        if x < p:
            return 1
        # coefficients
        arr = [0]*(x+1)
        arr[0] = 1
        m = p**k
        while m > 0:
            for i in range(m, x+1, m):
                arr[i] += arr[i-m]
            m //= p
        return arr[x]
    def A(n, k):
        p = 3
        return aseq(p, p*n, k)
    # A(n, k), 5 = A(3, 3) = aseq(3, 3*3, 3)
    # Serguei Zolotov, Mar 13 2019

Formula

G.f. of column k: 1/(1-x) * 1/Product_{j=0..k-1} (1 - x^(3^j)).
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