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.

Showing 1-10 of 20 results. Next

A340991 Triangle T(n,k) whose k-th column is the k-fold self-convolution of the primes; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 2, 0, 3, 4, 0, 5, 12, 8, 0, 7, 29, 36, 16, 0, 11, 58, 114, 96, 32, 0, 13, 111, 291, 376, 240, 64, 0, 17, 188, 669, 1160, 1120, 576, 128, 0, 19, 305, 1386, 3121, 4040, 3120, 1344, 256, 0, 23, 462, 2678, 7532, 12450, 12864, 8288, 3072, 512, 0, 29, 679, 4851, 16754, 34123, 44652, 38416, 21248, 6912, 1024
Offset: 0

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Author

Alois P. Heinz, Feb 01 2021

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0,  2;
  0,  3,   4;
  0,  5,  12,    8;
  0,  7,  29,   36,   16;
  0, 11,  58,  114,   96,    32;
  0, 13, 111,  291,  376,   240,    64;
  0, 17, 188,  669, 1160,  1120,   576,  128;
  0, 19, 305, 1386, 3121,  4040,  3120, 1344,  256;
  0, 23, 462, 2678, 7532, 12450, 12864, 8288, 3072, 512;
  ...
		

Crossrefs

Columns k=0-4 give (offsets may differ): A000007, A000040, A014342, A014343, A014344.
Main diagonal gives A000079.
Row sums give A030017(n+1).
T(2n,n) gives A340990.

Programs

  • Maple
    T:= proc(n, k) option remember; `if`(k=0, `if`(n=0, 1, 0),
          `if`(k=1, `if`(n=0, 0, ithprime(n)), (q->
           add(T(j, q)*T(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    seq(seq(T(n, k), k=0..n), n=0..12);
    # Uses function PMatrix from A357368.
    PMatrix(10, ithprime); # Peter Luschny, Oct 09 2022
  • Mathematica
    T[n_, k_] := T[n, k] = If[k == 0, If[n == 0, 1, 0],
         If[k == 1, If[n == 0, 0, Prime[n]], With[{q = Quotient[k, 2]},
         Sum[T[j, q] T[n - j, k - q], {j, 0, n}]]]];
    Table[Table[T[n, k], {k, 0, n}], {n, 0, 12}] // Flatten (* Jean-François Alcover, Feb 10 2021, after Alois P. Heinz *)

Formula

T(n,k) = [x^n] (Sum_{j>=1} prime(j)*x^j)^k.
Sum_{k=0..n} k * T(n,k) = A030281(n).
Sum_{k=0..n} (-1)^k * T(n,k) = A030018(n).
Conjecture: row polynomials are x*R(n,1) for n > 0 where R(n,k) = R(n-1,k+1) + x*R(n-1,1)*R(1,k) for n > 1, k > 0 with R(1,k) = prime(k) for k > 0. The same recursion seems to work for self-convolution of any other sequence. - Mikhail Kurkov, Apr 05 2025

A300662 Expansion of 1/(1 - x - Sum_{k>=2} prime(k-1)*x^k).

Original entry on oeis.org

1, 1, 3, 8, 22, 59, 160, 429, 1155, 3105, 8354, 22474, 60457, 162636, 437509, 1176941, 3166097, 8517138, 22912002, 61635707, 165806564, 446037175, 1199887133, 3227823181, 8683185454, 23358686444, 62837334885, 169039070970, 454732963567, 1223279724439, 3290751724917
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 10 2018

Keywords

Comments

Invert transform of A008578.

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(
         `if`(j=1, 1, ithprime(j-1))*a(n-j), j=1..n))
        end:
    seq(a(n), n=0..35);  # Alois P. Heinz, Mar 10 2018
  • Mathematica
    nmax = 30; CoefficientList[Series[1/(1 - x - Sum[Prime[k - 1] x^k, {k, 2, nmax}]), {x, 0, nmax}], x]
    p[1] = 1; p[n_] := p[n] = Prime[n - 1]; a[n_] := a[n] = Sum[p[k] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 30}]

Formula

G.f.: 1/(1 - Sum_{k>=1} A008578(k)*x^k).

A225127 Convolutory inverse of the nonprimes.

Original entry on oeis.org

1, -4, 10, -24, 59, -146, 360, -886, 2182, -5376, 13244, -32624, 80364, -197968, 487672, -1201319, 2959297, -7289859, 17957662, -44236464, 108971015, -268436517, 661259918, -1628931424, 4012669610, -9884711639, 24349755585, -59982589144, 147759635098
Offset: 1

Views

Author

Clark Kimberling, Apr 29 2013

Keywords

Comments

Coefficients in 1/(1+g(x)), where g is the generating functions of the sequence of nonprimes: (1,4,6,8,9,...). For the convolutory inverse of the primes, see A030018. Conjecture: a(n+1)/a(n) has a limit, -2.4633754095588889..., analogous to the Backhouse constant.
The sequences with nonzero first term form a group under convolution. The identity is (1,0,0,0,...), and the inverse of a sequence r(1), r(2), r(3), ... is s(1), s(2), s(3),... given by s(1) = 1/r(1) and s(n) = -(r(2)*s(n-1) + ... + r(n)*s(1))/r(1). Thus, s(i) are the coefficients of the power series for 1/(r(1) + r(2)*x + r(3)*x^2 + ... ).

Examples

			(1,4,6,8,9,...)**(1,-4,10,-24,59,...) = (1,0,0,0,0,...), where ** denotes convolution.
		

Crossrefs

Programs

  • Mathematica
    z = 1000; c = Complement[Range[z], Prime[Range[PrimePi[z]]]]; r[n_] := r[n] = c[[n]]; k[n_] := k[n] = 0; k[1] = 1; a[n_] := a[n] = (k[n] - Sum[r[i]*a[n - i + 1], {i, 2, n}])/r[1]; t = Table[a[n], {n, 1, 40}]   (* A225127 *)

A305882 -1 + Product_{n>=1} 1/(1 + a(n)*x^n) = g.f. of A000040 (prime numbers).

Original entry on oeis.org

-2, 1, 1, 4, 4, 13, 16, 44, 52, 112, 182, 411, 620, 1318, 2142, 5148, 7676, 15228, 27530, 58660, 98372, 207392, 364464, 763263, 1341508, 2773990, 4923220, 10470948, 18510902, 37546152, 69269976, 148419094, 258284232, 534761242, 981480012, 2004302204
Offset: 1

Views

Author

Ilya Gutkovskiy, Jun 13 2018

Keywords

Examples

			1/((1 - 2*x) * (1 + x^2) * (1 + x^3) * (1 + 4*x^4) * (1 + 4*x^5) * ... * (1 + a(n)*x^n) * ...) =  1 + 2*x + 3*x^2 + 5*x^3 + 7*x^4 + 11*x^5 + ... + A000040(k)*x^k + ...
		

Crossrefs

Formula

Product_{n>=1} 1/(1 + a(n)*x^n) = 1 + Sum_{k>=1} prime(k)*x^k.
Product_{n>=1} (1 + a(n)*x^n) = Sum_{k>=0} A030018(k)*x^k.

A225128 Numerators of the convolutory inverse of the primes of the form 4m+3.

Original entry on oeis.org

1, -7, 16, -52, 412, -2068, 6964, -19960, 81880, -396844, 1448908, -3853348, 9668860, -45544768, 238303744, -764868256, 1962327904, -9820441204, 62744531956, -306405293056, 1228176071080, -5276516025688, 26307346186816, -126143746044604, 534479888324932
Offset: 1

Views

Author

Clark Kimberling, Apr 29 2013

Keywords

Comments

Coefficients in 1/(1+g(x)), where g is the generating functions of the sequence of primes (3,7,11,19,23,31,...) of primes congruent to 3 mod 4. For the convolutory inverse of the primes, see A030018. Conjecture: a(n+1)/a(n) -> -1.370819405....

Examples

			(3,7,11,19,23,...)**(1/3, -7/9, 16/27, -52/81, 412/243,...) = (1,0,0,0,0,...), where ** denotes convolution.
		

Crossrefs

Programs

  • Mathematica
    q = {}; Do[If[PrimeQ[p = 4*n + 3], AppendTo[q, p]], {n, 0, 15000}]; r[n_] := q[[n]]; k[n_] := k[n] = 0; k[1] = 1; s[n_] := s[n] = (k[n] - Sum[r[k]*s[n - k + 1], {k, 2, n}])/r[1]; t = Table[s[n], {n, 1, 40}]; Numerator[t]

A225129 Numerators of the convolutory inverse of the primes of the form 4m+1.

Original entry on oeis.org

1, -13, 84, -712, 6916, -55788, 432584, -3555212, 28927916, -229458788, 1847086584, -14858027212, 118242773916, -945499611788, 7556178053084, -60048635124212, 477995366994916, -3810212526827288, 30296614848644584, -240796293647346212, 1916211884628153416
Offset: 1

Views

Author

Clark Kimberling, Apr 29 2013

Keywords

Comments

Coefficients in 1/(1+g(x)), where g is the generating functions of the sequence of primes (5,13,17,29,37,...) of primes congruent to 1 mod 4. For the convolutory inverse of the primes, see A030018. Conjecture: a(n+1)/a(n) -> -1.59045463062282....

Examples

			(5,13,17,29,37,...)**(1/5, -13/25, 84/125, -712/625, 6916/3125,...) = (1,0,0,0,0,...), where ** denotes convolution.
		

Crossrefs

Programs

  • Mathematica
    q = {}; Do[If[PrimeQ[p = 4*n + 1], AppendTo[q, p]], {n, 0, 15000}]; r[n_] := q[[n]]; k[n_] := k[n] = 0; k[1] = 1; s[n_] := s[n] = (k[n] - Sum[r[k]*s[n - k + 1], {k, 2, n}])/r[1]; t = Table[s[n], {n, 1, 40}]; Numerator[t]

A225130 Numerators of the convolutory inverse of the primes of the form 6m-1.

Original entry on oeis.org

1, -11, 36, -36, 36, -3786, 63786, -405036, 1215036, -4368786, 45022536, -380988786, 2242736286, -7681046286, 26949825036, -435049072536, 4543990507536, -25626723348786, 80068989783786, -100028016375036, 1579550678122536, -31186023693776286, 252408733196148786
Offset: 1

Views

Author

Clark Kimberling, Apr 29 2013

Keywords

Comments

Coefficients in 1/(1+g(x)), where g is the generating functions of the sequence of primes (5,11,17,23,29,...) of primes congruent to -1 mod 6. For the convolutory inverse of the primes, see A030018. Conjecture: a(n+1)/a(n) -> -1.24066....

Examples

			(5,11,17,23,29,...)**(1/5, -11/25, 36/125, -36/625, 36/3125,...) = (1,0,0,0,0,...), where ** denotes convolution.
		

Crossrefs

Programs

  • Mathematica
    q = {}; Do[If[PrimeQ[p = 6*n - 1], AppendTo[q, p]], {n, 0, 15000}]; r[n_] := q[[n]]; k[n_] := k[n] = 0; k[1] = 1; s[n_] := s[n] = (k[n] - Sum[r[k]*s[n - k + 1], {k, 2, n}])/r[1]; t = Table[s[n], {n, 1, 40}]; Numerator[t]

A225131 Numerators of the convolutory inverse of the primes of the form 6m+1.

Original entry on oeis.org

1, -13, 36, -258, 5622, -31716, -83460, 1766388, -2952900, 59171652, -2614259136, 25907667528, -87008484996, 410147565360, -10353918172170, 73320103253412, 409638469731702, -7210516315882284, 18236866211886120, -161388385633551558, 6594430509454957926
Offset: 1

Views

Author

Clark Kimberling, Apr 29 2013

Keywords

Comments

Coefficients in 1/(1+g(x)), where g is the generating functions of the sequence of primes (7,13,19,31,37,...) of primes congruent to 1 mod 6. For the convolutory inverse of the primes, see A030018. Conjecture: a(n+1)/a(n) diverges.

Examples

			(7,13,19,31,37,...)**(1/7, -13/49, 36/343, -258/2401, 5622/16807,...) = (1,0,0,0,0,...), where ** denotes convolution.
		

Crossrefs

Programs

  • Mathematica
    q = {}; Do[If[PrimeQ[p = 6*n - 1], AppendTo[q, p]], {n, 0, 15000}]; r[n_] := q[[n]]; k[n_] := k[n] = 0; k[1] = 1; s[n_] := s[n] = (k[n] - Sum[r[k]*s[n - k + 1], {k, 2, n}])/r[1]; t = Table[s[n], {n, 1, 40}]; Numerator[t]

A307898 Expansion of 1/(1 - x * Sum_{k>=1} prime(k)*x^k).

Original entry on oeis.org

1, 0, 2, 3, 9, 19, 48, 107, 258, 594, 1405, 3277, 7693, 18004, 42203, 98834, 231592, 542497, 1271003, 2977529, 6975674, 16342011, 38285178, 89691782, 210124363, 492265243, 1153247379, 2701752062, 6329489153, 14828313076, 34738805240, 81383803849, 190660665579, 446667359857, 1046423138962
Offset: 0

Views

Author

Ilya Gutkovskiy, May 04 2019

Keywords

Comments

Antidiagonal sums of square array, in which row m equals the m-fold convolution of primes with themselves.

Crossrefs

Programs

  • Mathematica
    nmax = 34; CoefficientList[Series[1/(1 - x Sum[Prime[k] x^k, {k, 1, nmax}]), {x, 0, nmax}], x]
    a[0] = 1; a[n_] := a[n] = Sum[Prime[k] a[n - k - 1], {k, 1, n - 1}]; Table[a[n], {n, 0, 34}]

Formula

Recurrence: a(n+1) = Sum_{k=1..n} prime(k)*a(n-k).

A307899 Expansion of 1/(1 + x * Sum_{k>=1} prime(k)*x^k).

Original entry on oeis.org

1, 0, -2, -3, -1, 5, 10, 9, -4, -26, -43, -33, 35, 148, 219, 98, -316, -857, -983, 23, 2296, 4501, 3712, -2906, -14257, -21771, -10811, 28282, 81209, 97292, 7960, -207185, -431595, -386033, 219344, 1322141, 2134126, 1226554, -2443765, -7684081, -9726127, -1791806, 18712361, 41428590, 39753658
Offset: 0

Views

Author

Ilya Gutkovskiy, May 04 2019

Keywords

Comments

Alternating antidiagonal sums of square array, in which row m equals the m-fold convolution of primes with themselves.

Crossrefs

Programs

  • Mathematica
    nmax = 44; CoefficientList[Series[1/(1 + x Sum[Prime[k] x^k, {k, 1, nmax}]), {x, 0, nmax}], x]
    a[0] = 1; a[n_] := a[n] = -Sum[Prime[k] a[n - k - 1], {k, 1, n - 1}]; Table[a[n], {n, 0, 44}]

Formula

Recurrence: a(n+1) = -Sum_{k=1..n} prime(k)*a(n-k).
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