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 1-3 of 3 results.

A129360 A054525 * A115361.

Original entry on oeis.org

1, 0, 1, -1, 0, 1, 0, 0, 0, 1, -1, 0, 0, 0, 1, 0, -1, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, -1, 0, 0, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
Offset: 1

Views

Author

Gary W. Adamson, Apr 10 2007

Keywords

Comments

Row sums = A209229 (1, 1, 0, 1, 0, 0, 0, 1, ...).
A129353 = the inverse Möbius transform of A115361.

Examples

			First few rows of the triangle are:
   1;
   0,  1;
  -1,  0,  1;
   0,  0,  0,  1;
  -1,  0,  0,  0,  1;
   0, -1,  0,  0,  0,  1;
  -1,  0,  0,  0,  0,  0,  1;
   0,  0,  0,  0,  0,  0,  0,  1;
  ...
		

Crossrefs

Column 1 is A087003 (Moebius transform of A209229).
Row sums are A209229.

Programs

  • PARI
    tabl(nn) = {Tm = matrix(nn, nn, n, k, if (! (n % k), moebius(n/k), 0)); Tr = matrix(nn, nn, n, k, n--; k--; if ((n==k), 1, if (n==2*k+1, -1, 0))); Ti = Tr^(-1); Tp = Tm*Ti; for (n=1, nn, for (k=1, n, print1(Tp[n, k], ", ");); print(););} \\ Michel Marcus, Mar 28 2015
    
  • PARI
    T(n, k)={ if(n%k, 0, sumdiv(n/k, d, my(e=valuation(d, 2)); if(d==1<Andrew Howroyd, Aug 03 2018

Formula

Moebius transform of A115361.
T(n,k) = A087003(n/k) for k | n, T(n,k) = 0 otherwise. - Andrew Howroyd, Aug 03 2018

Extensions

More terms from Michel Marcus, Mar 28 2015
Offset changed by Andrew Howroyd, Aug 03 2018

A129502 For n=2^k, a(n) = binomial(k + 2, 2), else 0.

Original entry on oeis.org

1, 3, 0, 6, 0, 0, 0, 10, 0, 0, 0, 0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 28, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Gary W. Adamson, Apr 17 2007

Keywords

Comments

Row sums of triangle A129501.

Examples

			a(4) = 6 = sum of A129501 terms: (3 + 2 + 0 + 1).
		

Crossrefs

Programs

  • Mathematica
    Table[If[IntegerQ[Log2[n]],Binomial[Log2[n]+2,2],0],{n,100}] (* Harvey P. Dale, May 10 2022 *)
  • PARI
    a(n)={my(e=valuation(n, 2)); if(n==1<Andrew Howroyd, Aug 03 2018

Formula

From Andrew Howroyd, Aug 04 2018: (Start)
Multiplicative with a(2^e) = binomial(e + 2, 2), a(p^e) = 0 for odd prime p.
Dirichlet convolution of A104117 and A209229.
a(n) = Sum_{d|n} A104117(n/d) * A209229(d). (End)
Dirichlet g.f.: 1/(1 - 1/2^s)^3. - Amiram Eldar, Oct 28 2023

Extensions

Name changed and terms a(40) and beyond from Andrew Howroyd, Aug 03 2018

A317673 Moebius transform of A129502.

Original entry on oeis.org

1, 2, -1, 3, -1, -2, -1, 4, 0, -2, -1, -3, -1, -2, 1, 5, -1, 0, -1, -3, 1, -2, -1, -4, 0, -2, 0, -3, -1, 2, -1, 6, 1, -2, 1, 0, -1, -2, 1, -4, -1, 2, -1, -3, 0, -2, -1, -5, 0, 0, 1, -3, -1, 0, 1, -4, 1, -2, -1, 3, -1, -2, 0, 7, 1, 2, -1, -3, 1, 2, -1, 0, -1
Offset: 1

Views

Author

Andrew Howroyd, Aug 03 2018

Keywords

Comments

Dirichlet convolution of A209635 and A209229.

Crossrefs

First column of A129501.
Cf. A129502, A209229, A209635 (Moebius transform of A104117).

Programs

  • Mathematica
    a[n_] := Module[{e}, Sum[e = IntegerExponent[d, 2]; If[d == 2^e, MoebiusMu[n/d] Binomial[2 + e, 2], 0], {d, Divisors[n]}]];
    a /@ Range[1, 100] (* Jean-François Alcover, Sep 24 2019, from PARI *)
    f[p_, e_] := If[e == 1, -1, 0]; f[2, e_] := e+1; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 70] (* Amiram Eldar, Aug 28 2023 *)
  • PARI
    a(n)={sumdiv(n, d,  my(e=valuation(d, 2)); if(d==1<
    				

Formula

Multiplicative with a(2^e) = e+1, and if p is an odd prime, a(p) = -1 and a(p^e) = 0 for e >= 2. - Amiram Eldar, Aug 28 2023
Showing 1-3 of 3 results.