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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A349567 Dirichlet convolution of A133494 [3^(n-1)] with A349452 (Dirichlet inverse of A011782, 2^(n-1)).

Original entry on oeis.org

1, 1, 5, 17, 65, 197, 665, 2017, 6285, 19025, 58025, 174565, 527345, 1584737, 4766245, 14311841, 42981185, 128995317, 387158345, 1161697825, 3485732845, 10458138977, 31376865305, 94134428213, 282412758225, 847253996225, 2541798693045, 7625460083185, 22876524019505, 68629830861205, 205890058352825, 617671220125537
Offset: 1

Views

Author

Antti Karttunen, Nov 22 2021

Keywords

Comments

Dirichlet convolution of this sequence with A034738 produces A034754.

Crossrefs

Cf. A011782, A133494, A349452, A349568 (Dirichlet inverse).

Programs

  • Mathematica
    s[1] = 1; s[n_] := s[n] = -DivisorSum[n, s[#] * 2^(n/# - 1) &, # < n &]; a[n_] := DivisorSum[n, 3^(# - 1) * s[n/#] &]; Array[a, 32] (* Amiram Eldar, Nov 22 2021 *)
  • PARI
    A011782(n) = (2^(n-1));
    memoA349452 = Map();
    A349452(n) = if(1==n,1,my(v); if(mapisdefined(memoA349452,n,&v), v, v = -sumdiv(n,d,if(dA011782(n/d)*A349452(d),0)); mapput(memoA349452,n,v); (v)));
    A349567(n) = sumdiv(n,d,(3^(d-1)) * A349452(n/d));

Formula

a(n) = Sum_{d|n} 3^(d-1) * A349452(n/d).

A349569 Dirichlet convolution of A000027 (identity function) with A349452 (Dirichlet inverse of A011782, 2^(n-1)).

Original entry on oeis.org

1, 0, -1, -4, -11, -24, -57, -112, -243, -480, -1013, -1964, -4083, -8064, -16309, -32496, -65519, -130440, -262125, -523156, -1048263, -2095104, -4194281, -8383760, -16777015, -33546240, -67107609, -134200860, -268435427, -536835096, -1073741793, -2147417216, -4294962187, -8589803520, -17179867533, -34359463812
Offset: 1

Views

Author

Antti Karttunen, Nov 22 2021

Keywords

Comments

Dirichlet convolution with A034729 gives sigma, A000203, and convolution with A034738 gives A018804.

Crossrefs

Cf. A000027, A011782, A349452, A349570 (Dirichlet inverse).

Programs

  • Mathematica
    s[1] = 1; s[n_] := s[n] = -DivisorSum[n, s[#]*2^(n/# - 1) &, # < n &]; a[n_] := DivisorSum[n, # * s[n/#] &]; Array[a, 36] (* Amiram Eldar, Nov 22 2021 *)
  • PARI
    A011782(n) = (2^(n-1));
    memoA349452 = Map();
    A349452(n) = if(1==n,1,my(v); if(mapisdefined(memoA349452,n,&v), v, v = -sumdiv(n,d,if(dA011782(n/d)*A349452(d),0)); mapput(memoA349452,n,v); (v)));
    A349569(n) = sumdiv(n,d,d * A349452(n/d));

Formula

a(n) = Sum_{d|n} d * A349452(n/d).

A055852 Convolution of A055589 with A011782.

Original entry on oeis.org

0, 1, 7, 34, 138, 501, 1683, 5336, 16172, 47264, 134048, 370688, 1003136, 2664192, 6960384, 17922048, 45552640, 114442240, 284508160, 700579840, 1710161920, 4141416448, 9955639296, 23770693632, 56400543744, 133041225728
Offset: 0

Views

Author

Wolfdieter Lang May 30 2000

Keywords

Comments

Seventh column of triangle A055587.
T(n,5) of array T as in A049600.

Crossrefs

Programs

  • GAP
    a:=[1,7,34,138,501,1683];; for n in [7..30] do a[n]:=12*a[n-1] -60*a[n-2] +160*a[n-3] -240*a[n-4] +192*a[n-5] -64*a[n-6]; od; Concatenation([0], a); # G. C. Greubel, Jan 16 2020
  • Magma
    R:=PowerSeriesRing(Integers(), 30); [0] cat Coefficients(R!( x*(1-x)^5/(1-2*x)^6 )); // G. C. Greubel, Jan 16 2020
    
  • Maple
    seq(coeff(series(x*(1-x)^5/(1-2*x)^6, x, n+1), x, n), n = 0..30); # G. C. Greubel, Jan 16 2020
  • Mathematica
    CoefficientList[Series[x*(1-x)^5/(1-2*x)^6, {x,0,30}], x] (* G. C. Greubel, Jan 16 2020 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x*(1-x)^5/(1-2*x)^6)) \\ G. C. Greubel, Jan 16 2020
    
  • Sage
    def A055852_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x*(1-x)^5/(1-2*x)^6 ).list()
    A055852_list(30) # G. C. Greubel, Jan 16 2020
    

Formula

a(n) = T(n, 5) = A055587(n+5, 6).
G.f.: x*(1-x)^5/(1-2*x)^6.

A290222 Multiset transform of A011782, powers of 2: 1, 2, 4, 8, 16, ...

Original entry on oeis.org

1, 0, 1, 0, 2, 1, 0, 4, 2, 1, 0, 8, 7, 2, 1, 0, 16, 16, 7, 2, 1, 0, 32, 42, 20, 7, 2, 1, 0, 64, 96, 54, 20, 7, 2, 1, 0, 128, 228, 140, 59, 20, 7, 2, 1, 0, 256, 512, 360, 156, 59, 20, 7, 2, 1, 0, 512, 1160, 888, 422, 162, 59, 20, 7, 2, 1, 0, 1024, 2560, 2168, 1088, 442, 162, 59, 20, 7, 2, 1
Offset: 0

Views

Author

M. F. Hasler, Jul 24 2017

Keywords

Comments

T(n,k) is the number of multisets of exactly k binary words with a total of n letters and each word beginning with 1. T(4,2) = 7: {1,100}, {1,101}, {1,110}, {1,111}, {10,10}, {10,11}, {11,11}. - Alois P. Heinz, Sep 18 2017

Examples

			The triangle starts:
1;
0    1;
0    2    1;
0    4    2    1;
0    8    7    2    1;
0   16   16    7    2   1;
0   32   42   20    7   2   1;
0   64   96   54   20   7   2  1;
0  128  228  140   59  20   7  2  1;
0  256  512  360  156  59  20  7  2  1;
0  512 1160  888  422 162  59 20  7  2  1;
0 1024 2560 2168 1088 442 162 59 20  7  2  1;
(...)
		

Crossrefs

Cf. A034691 (row sums), A000007 (column k=0), A011782 (column k=1), A178945(n-1) (column k=2).
The reverse of the n-th row converges to A034899.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(p>n, 0, `if`(n=0, 1,
          `if`(min(i, p)<1, 0, add(binomial(2^(i-1)+j-1, j)*
             b(n-i*j, i-1, p-j), j=0..min(n/i, p)))))
        end:
    T:= (n, k)-> b(n$2, k):
    seq(seq(T(n, k), k=0..n), n=0..14);  # Alois P. Heinz, Sep 12 2017
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[p > n, 0, If[n == 0, 1, If[Min[i, p] < 1, 0, Sum[Binomial[2^(i - 1) + j - 1, j] b[n - i j, i - 1, p - j], {j, 0, Min[n/i, p]}]]]];
    T[n_, k_] := b[n, n, k];
    Table[Table[T[n, k], {k, 0, n}], {n, 0, 14}] // Flatten (* Jean-François Alcover, Dec 07 2019, after Alois P. Heinz *)

Formula

G.f.: 1 / Product_{j>=1} (1-y*x^j)^(2^(j-1)). - Alois P. Heinz, Sep 18 2017

A349564 Dirichlet convolution of A011782 [2^(n-1)] with A349450 [Dirichlet inverse of right-shifted Catalan numbers].

Original entry on oeis.org

1, 1, 2, 2, 2, -14, -68, -308, -1178, -4366, -15772, -56780, -203916, -734772, -2658088, -9662208, -35292134, -129514026, -477376556, -1766739436, -6563071972, -24464170892, -91478369336, -343051227304, -1289887370136, -4861912851116, -18367285963792, -69533416706328, -263747683314904, -1002241679797688
Offset: 1

Views

Author

Antti Karttunen, Nov 22 2021

Keywords

Comments

Dirichlet convolution with A034731 gives A034729.

Crossrefs

Cf. A000108, A011782, A349452, A349563 (Dirichlet inverse).

Programs

  • Mathematica
    s[1] = 1; s[n_] := s[n] = -DivisorSum[n, s[#] * CatalanNumber[n/# - 1] &, # < n &]; a[n_] := DivisorSum[n, 2^(# - 1) * s[n/#] &]; Array[a, 30] (* Amiram Eldar, Nov 22 2021 *)
  • PARI
    A000108(n) = (binomial(2*n, n)/(n+1));
    memoA349450 = Map();
    A349450(n) = if(1==n,1,my(v); if(mapisdefined(memoA349450,n,&v), v, v = -sumdiv(n,d,if(dA000108((n/d)-1)*A349450(d),0)); mapput(memoA349450,n,v); (v)));
    A349564(n) = sumdiv(n,d,2^(d-1)*A349450(n/d));

Formula

a(n) = Sum_{d|n} 2^(d-1) * A349450(n/d).

A349568 Dirichlet convolution of A011782 [2^(n-1)] with A349453 (Dirichlet inverse of A133494, 3^(n-1)).

Original entry on oeis.org

1, -1, -5, -16, -65, -187, -665, -1984, -6260, -18895, -58025, -174016, -527345, -1583407, -4765595, -14307568, -42981185, -128980852, -387158345, -1161657760, -3485726195, -10458022927, -31376865305, -94134053296, -282412754000, -847252941535, -2541798630320, -7625456893096, -22876524019505, -68629821114805
Offset: 1

Views

Author

Antti Karttunen, Nov 22 2021

Keywords

Comments

Dirichlet convolution of this sequence with A034754 produces A034738.

Crossrefs

Cf. A011782, A133494, A349453, A349567 (Dirichlet inverse).

Programs

  • Mathematica
    s[1] = 1; s[n_] := s[n] = -DivisorSum[n, s[#] * 3^(n/# - 1) &, # < n &]; a[n_] := DivisorSum[n, 2^(# - 1) * s[n/#] &]; Array[a, 30] (* Amiram Eldar, Nov 22 2021 *)
  • PARI
    A133494(n) = max(1, 3^(n-1));
    memoA349453 = Map();
    A349453(n) = if(1==n,1,my(v); if(mapisdefined(memoA349453,n,&v), v, v = -sumdiv(n,d,if(dA133494(n/d)*A349453(d),0)); mapput(memoA349453,n,v); (v)));
    A349568(n) = sumdiv(n,d,(2^(d-1)) * A349453(n/d));

Formula

a(n) = Sum_{d|n} 2^(d-1) * A349453(n/d).

A055589 Convolution of A049612 with A011782.

Original entry on oeis.org

0, 1, 6, 26, 96, 321, 1002, 2972, 8472, 23392, 62912, 165504, 427264, 1085184, 2717184, 6718464, 16427008, 39763968, 95387648, 226951168, 535953408, 1257046016, 2929852416, 6789267456, 15648423936, 35888562176, 81927340032
Offset: 0

Views

Author

Wolfdieter Lang May 30 2000

Keywords

Comments

Sixth column of triangle A055587. T(n,4) of array T as in A049600.

Crossrefs

Formula

a(n)= T(n, 4)= A055587(n+4, 5).
G.f.: x*((1-x)^4)/(1-2*x)^5.

A055853 Convolution of A055852 with A011782.

Original entry on oeis.org

0, 1, 8, 43, 190, 743, 2668, 8989, 28814, 88720, 264224, 765088, 2162624, 5986304, 16268800, 43499264, 114629120, 298147840, 766361600, 1948794880, 4907171840, 12245598208, 30305419264, 74425892864, 181481635840, 439603953664
Offset: 0

Views

Author

Wolfdieter Lang May 30 2000

Keywords

Comments

Eighth column of triangle A055587.
T(n,6) of array T as in A049600.

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 30); [0] cat Coefficients(R!( x*(1-x)^6/(1-2*x)^7 )); // G. C. Greubel, Jan 16 2020
    
  • Maple
    seq(coeff(series(x*(1-x)^6/(1-2*x)^7, x, n+1), x, n), n = 0..30); # G. C. Greubel, Jan 16 2020
  • Mathematica
    CoefficientList[Series[x*(1-x)^6/(1-2*x)^7, {x,0,30}], x] (* G. C. Greubel, Jan 16 2020 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x*(1-x)^6/(1-2*x)^7)) \\ G. C. Greubel, Jan 16 2020
    
  • Sage
    def A055853_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x*(1-x)^6/(1-2*x)^7 ).list()
    A055853_list(30) # G. C. Greubel, Jan 16 2020

Formula

a(n) = T(n, 6)= A055587(n+6, 7).
G.f.: x*(1-x)^6/(1-2*x)^7.

A125107 Subtract compositions (A011782) from Catalan numbers (A000108).

Original entry on oeis.org

0, 0, 0, 1, 6, 26, 100, 365, 1302, 4606, 16284, 57762, 205964, 738804, 2666248, 9678461, 35324902, 129579254, 477507628, 1767001046, 6563596132, 24465218444, 91480466488, 343055419346, 1289895758716, 4861929624236, 18367319517720, 69533483807140, 263747817532632
Offset: 0

Views

Author

Alford Arnold, Dec 15 2006

Keywords

Comments

Apparently the number of Dyck n-paths with more than half of the path lying between the first and last peaks. - David Scambler, Sep 14 2012
From Peter Luschny, Nov 28 2024: (Start)
A Touchard walk T(n) of length n is, as defined by Dershowitz, "a sequence of n steps, each of which is one of N/S/E/W, such that at each point along the way the number of N-steps that have been taken is never less than the number of S-steps, and are in the end equal."
There are Sum_{k=0..n} binomial(n, k) Touchard walks that have no N/S-steps at all and since by Touchard's identity T(n) = Catalan(n+1), it follows that a(n) = T(n-1) - Sum_{k=0..n-1} binomial(n-1, k) = Catalan(n) - 2^(n-1) for n >= 1. Thus a(n+1) is the number of Touchard walks of length n that have at least one N-step. (End)

Examples

			A000108 begins 1 1 2 5 14 42 132 429 ...
A011782 begins 1 1 2 4  8 16  32  64 ...
so we get .... 0 0 0 1  6 26 100 365 ...
.
The 26 Touchard walks of length 4 that have at least one N-step are:
   NNSS, NSNS, NSEE, NSEW, NSWE, NSWW, NESE, NESW, NWSE,
   NWSW, NEES, NEWS, NWES, NWWS, ENSE, ENSW, WNSE, WNSW,
   ENES, ENWS, WNES, WNWS, EENS, EWNS, WENS, WWNS.
		

Crossrefs

Cf. A000079, A000108, A000110, A011782, A016098, A097805, A091894 (Touchard distribution), A377659 (similar with Motzkin).

Programs

  • Maple
    # From Peter Luschny, Nov 28 2024: (Start)
    a := n -> ifelse(n = 0, 0, binomial(2*n, n)/(n+1) - 2^(n-1)): seq(a(n), n = 0..28);
    # Series expansion:
    gf := (1 - sqrt(1 - 4*x)) / (2*x) - (1 - x) / (1 - 2*x): ser := series(gf, x, 30): seq(coeff(ser, x, n), n = 0..28);
    # Evaluating polynomials:
    p := (n, x) -> ifelse(n = 0, 0, 2^(n-1)*(hypergeom([1 - n/2, 1/2 - n/2], [2], x) - 1)): seq(subs(x = 1, expand(simplify(p(n, x)))), n = 0..28);  # (End)
  • Mathematica
    Table[CatalanNumber[n] - If[n==0, 1, 2^(n-1)], {n, 0, 30}] (* David Scambler, Sep 14 2012 *)
  • Python
    # Generates the walks (for illustration only).
    C = str.count
    def aGen(n: int) -> Generator[str, Any, list[str]]:
        a = [""]
        if n <= 0: return a
        for w in a:
            if len(w) == n - 1:
                if C(w, "N") > 0 and C(w, "N") == C(w, "S"):
                    yield w
            else:
                for j in "NSEW":
                    U = w + j
                    if C(U, "N") >= C(U, "S"):
                        a += [U]
        return a
    for n in range(6): print([w for w in aGen(n)])  # Peter Luschny, Dec 03 2024

Formula

a(n) = A000108(n) - A011782(n).
(n+1)*a(n) + 2*(1-4*n)*a(n-1) + 4*(5*n-7)*a(n-2) + 8*(5-2*n)*a(n-3) = 0. - R. J. Mathar, Aug 10 2013
From Peter Luschny, Nov 28 2024: (Start)
a(n) = [x^n] (1 - sqrt(1 - 4*x)) / (2*x) - (1 - x) / (1 - 2*x).
a(n) = n! * [x^n] (exp(2*x)*(BesselI_{0}(2*x) - BesselI_{1}(2*x) - 1/2) - 1/2).
a(n) = p(n, 1) for n >= 1, where p(n, x) = 2^(n-1)*(hypergeom([1-n/2, (1-n)/2], [2], x) - 1).
a(n) = Sum_{k=0..n} (A091894(n, k) - A097805(n, n-k)). (End)

Extensions

More terms from David Scambler, Sep 14 2012

A349570 Dirichlet convolution of A011782 [2^(n-1)] with A055615 (Dirichlet inverse of n).

Original entry on oeis.org

1, 0, 1, 4, 11, 24, 57, 112, 244, 480, 1013, 1972, 4083, 8064, 16331, 32512, 65519, 130488, 262125, 523244, 1048377, 2095104, 4194281, 8384176, 16777136, 33546240, 67108096, 134201316, 268435427, 536836584, 1073741793, 2147418112, 4294964213, 8589803520, 17179868787, 34359470272, 68719476699, 137438429184, 274877894643
Offset: 1

Views

Author

Antti Karttunen, Nov 22 2021

Keywords

Comments

Dirichlet convolution of this sequence with phi (A000010) is A000740, with sigma (A000203) it is A034729, and with A018804 it is A034738.

Crossrefs

Cf. A011782, A055615, A349569 (Dirichlet inverse).

Programs

  • Mathematica
    a[n_] := DivisorSum[n, # * MoebiusMu[#] * 2^(n/# - 1) &]; Array[a, 40] (* Amiram Eldar, Nov 22 2021 *)
  • PARI
    A055615(n) = (n*moebius(n));
    A349570(n) = sumdiv(n,d,(2^(d-1)) * A055615(n/d));

Formula

a(n) = Sum_{d|n} 2^(d-1) * A055615(n/d).
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