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 99 results. Next

A168532 Triangle read by rows, A054525 * A168021.

Original entry on oeis.org

1, 1, 1, 2, 0, 1, 3, 1, 0, 1, 6, 0, 0, 0, 1, 7, 2, 1, 0, 0, 1, 14, 0, 0, 0, 0, 0, 1, 17, 3, 0, 1, 0, 0, 0, 1, 27, 0, 2, 0, 0, 0, 0, 0, 1, 34, 6, 0, 0, 1, 0, 0, 0, 0, 1, 55, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 63, 7, 3, 2, 0, 1, 0, 0, 0, 0, 0, 1, 100, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
Offset: 1

Views

Author

Gary W. Adamson, Nov 28 2009

Keywords

Comments

Row sums = A000041 starting (1, 2, 3, 5, 7, 11, 15, ...).
T(n,k) is the number of partitions of n into parts with GCD = k. - Alois P. Heinz, Jun 06 2013

Examples

			First few rows of the triangle:
    1;
    1,  1;
    2,  0, 1;
    3,  1, 0, 1;
    6,  0, 0, 0, 1;
    7,  2, 1, 0, 0, 1;
   14,  0, 0, 0, 0, 0, 1;
   17,  3, 0, 1, 0, 0, 0, 1;
   27,  0, 2, 0, 0, 0, 0, 0, 1;
   34,  6, 0, 0, 1, 0, 0, 0, 0, 1;
   55,  0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
   63,  7, 3, 2, 0, 1, 0, 0, 0, 0, 0, 1;
  100,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
  119, 14, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1;
  167,  0, 6, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
  209, 17, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1;
  296,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
  ...
		

Crossrefs

Cf. A256067 (the same for LCM).

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i=1, x,
          b(n, i-1)+(p-> add(coeff(p, x, t)*x^igcd(t, i),
          t=0..degree(p)))(add(b(n-i*j, i-1), j=1..n/i))))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=1..n))(b(n$2)):
    seq(T(n), n=1..17);  # Alois P. Heinz, Mar 29 2015
  • Mathematica
    b[n_, i_] := b[n, i] = If[n==0, 1, If[i==1, x, b[n, i-1] + Function[{p}, Sum[Coefficient[p, x, t]*x^GCD[t, i], {t, 0, Exponent[p, x]}]][Sum[b[n - i*j, i-1], {j, 1, n/i}]]]]; T[n_] := Function[{p}, Table[Coefficient[p, x, i], {i, 1, n}]][b[n, n]]; Table[T[n], {n, 1, 17}] // Flatten (* Jean-François Alcover, Jan 08 2016, after Alois P. Heinz *)

Formula

Mobius transform of triangle A168021 = an infinite lower triangular matrix with aerated variants of A000837 in each column; where A000837 = the Mobius transform of the partition numbers, A000041.

Extensions

Corrected and extended by Alois P. Heinz, Jun 06 2013

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

A143519 Moebius transform of A010051, the characteristic function of the primes: a(n) = Sum_{d|n} mu(n/d)*A010051(d); A054525 * A010051.

Original entry on oeis.org

0, 1, 1, -1, 1, -2, 1, 0, -1, -2, 1, 1, 1, -2, -2, 0, 1, 1, 1, 1, -2, -2, 1, 0, -1, -2, 0, 1, 1, 3, 1, 0, -2, -2, -2, 0, 1, -2, -2, 0, 1, 3, 1, 1, 1, -2, 1, 0, -1, 1, -2, 1, 1, 0, -2, 0, -2, -2, 1, -1, 1, -2, 1, 0, -2, 3, 1, 1, -2, 3, 1, 0, 1, -2, 1, 1, -2, 3, 1, 0, 0, -2, 1, -1, -2, -2, -2, 0, 1
Offset: 1

Views

Author

Gary W. Adamson, Aug 22 2008

Keywords

Comments

A010051 = A051731 * A143519 (since A051731 = the inverse Mobius transform).
A000720(n) = Sum_{k=1..n} a(k) floor(n/k) where A000720(n) is the number of primes <= n. - Steven Foster Clark, May 25 2018

Examples

			a(4) = -1 since row 4 of triangle A043518 = (0, -1, 0, 0).
a(4) = -1 = (0, -1, 0, 1) dot (0, 1, 1, 0), where (0, -1, 0, 1) = row 4 of A054525 and A010051 = (0, 1, 1, 0, 1, 0, 1, 0, ...).
		

Crossrefs

Programs

  • Mathematica
    Table[Sum[MoebiusMu[n/d] Boole[PrimeQ@ d], {d, Divisors@ n}], {n, 89}] (* Michael De Vlieger, Jul 19 2017 *)
  • PARI
    A143519(n) = sumdiv(n,d,isprime(d)*moebius(n/d)); \\ (After Luschny's Sage-code) - Antti Karttunen, Jul 19 2017
  • Sage
    def A143519(n) :
        D = filter(is_prime, divisors(n))
        return add(moebius(n/d) for d in D)
    [A143519(n) for n in (1..89)]   # Peter Luschny, Feb 01 2012
    

Formula

Mobius transform of A010051, the characteristic function of the primes.
Row sums of triangle A143518.
a(n) = Sum_{d|n} A010051(d)*A008683(n/d). - Antti Karttunen, Jul 19 2017
a(n) = Sum_{a*b*c=n} omega(a)*mu(b)*mu(c). - Benedict W. J. Irwin, Mar 02 2022

Extensions

More terms from R. J. Mathar, Jan 19 2009

A134541 Triangle read by rows: A000012 * A054525 regarded as infinite lower triangular matrices.

Original entry on oeis.org

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

Views

Author

Gary W. Adamson, Oct 31 2007

Keywords

Comments

Row sums = 1.
Left border = A002321, the Mertens function.
A134541 * [1,2,3,...] = A002088: (1, 2, 4, 6, 10, 12, 18, 22, ...).

Examples

			First few rows of the triangle:
   1;
   0,  1;
  -1,  1,  1;
  -1,  0,  1, 1;
  -2,  0,  1, 1, 1;
  -1, -1,  0, 1, 1, 1;
  -2, -1,  0, 1, 1, 1, 1;
  -2, -1,  0, 0, 1, 1, 1, 1;
  -2, -1, -1, 0, 1, 1, 1, 1, 1;
  -1, -2, -1, 0, 0, 1, 1, 1, 1, 1;
  ...
		

Crossrefs

Matrix inverse of A176702. - Mats Granvik, Apr 24 2010

Programs

  • Mathematica
    Clear[t, s, n, k, z, x]; z = 1; nn = 10; t[n_, k_] := t[n, k] = If[n >= k, If[k == 1, 1 - Sum[t[n, k + i]/(i + 1)^(s - 1), {i, 1, n - 1}], t[Floor[n/k], 1]], 0]; Flatten[Table[Table[Limit[t[n, k], s -> z], {k, 1, n}], {n, 1, nn}]] (* Mats Granvik, Jul 22 2012 *) (* updated Mats Granvik, Apr 10 2016 *)

Formula

Recurrence: T(n, k) = If n >= k then If k = 1 then 1 - Sum_{i=1..n-1} T(n, k + i)/(i + 1)^(s - 1) else T(floor(n/k) else 1)) else 0). - Mats Granvik, Apr 17 2016

Extensions

More terms from Amiram Eldar, Jun 09 2024

A127466 Triangle read by rows: A054525 * A127481 as infinite lower triangular matrices.

Original entry on oeis.org

1, 2, 2, 3, 0, 6, 4, 4, 0, 8, 5, 0, 0, 0, 20, 6, 6, 12, 0, 0, 12, 7, 0, 0, 0, 0, 0, 42, 8, 8, 0, 16, 0, 0, 0, 32, 9, 0, 18, 0, 0, 0, 0, 0, 54, 10, 10, 0, 0, 40, 0, 0, 0, 0, 40
Offset: 1

Views

Author

Gary W. Adamson, Jan 15 2007

Keywords

Comments

Mobius transform of A127481.

Examples

			First few rows of the triangle are:
1;
2, 2;
3, 0, 6;
4, 4, 0, 8;
5, 0, 0, 0, 20;
6, 6, 12, 0, 0, 12;
7, 0, 0, 0, 0, 0, 42;
8, 8, 0, 16, 0, 0, 0, 32;
...
		

Crossrefs

Programs

Formula

Sum_{k=1..n} T(n,k) = n^2.
T(n,n) = A002618(n) = n*phi(n).

Extensions

Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Aug 23 2007

A137851 a(n) = A054525(n) * A061397(n).

Original entry on oeis.org

0, 2, 3, -2, 5, -5, 7, 0, -3, -7, 11, 2, 13, -9, -8, 0, 17, 3, 19, 2, -10, -13, 23, 0, -5, -15, 0, 2, 29, 10, 31, 0, -14, -19, -12, 0, 37, -21, -16, 0, 41, 12, 43, 2, 3, -25, 47, 0, -7, 5, -20, 2, 53, 0, -16, 0, -22, -31, 59, -2, 61, -33, 3, 0, -18, 16, 67, 2, -26, 14, 71, 0, 73, -39, 5, 2, -18, 18, 79, 0, 0, -43, 83, -2, -22, -45, -32, 0
Offset: 1

Views

Author

Gary W. Adamson, Feb 14 2008

Keywords

Comments

Equals row sums of triangle A143517. - Gary W. Adamson, Aug 22 2008

Examples

			a(4) = -2 = (0, -1, 0, 1) dot (0, 2, 3, 0), where (0, -1, 0, 1) = row 4 of the Möbius triangle A054525 and (0, 2, 3, 0) = the first 4 terms of A061397.
		

Crossrefs

Programs

  • Maple
    A061397 := proc(n) if isprime(n) then n; else 0 ; fi ; end: A054525 := proc(n,k) if n mod k = 0 then numtheory[mobius](n/k); else 0; fi ; end: A137851 := proc(n) local k ; add(A061397(k)* A054525(n,k),k=1..n) ; end: seq(A137851(n),n=1..120) ; # R. J. Mathar, May 23 2008
  • Mathematica
    a[n_] := If[n == 1, 0, With[{p = FactorInteger[n][[All, 1]]}, p*MoebiusMu[n/p] // Total]];
    Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Jun 13 2023 *)
  • Sage
    def A137851(n):
        return add(d*moebius(n//d) for d in divisors(n) if is_prime(d))
    [A137851(n) for n in (1..88)] # Peter Luschny, Feb 01 2012

Formula

A054525 * A061397 = Möbius transform of [0, 2, 3, 0, 5, 0, 7, 0, 0, 0, 11, 0, 13, ...].
Dirichlet g.f.: primezeta(s-1)/zeta(s). - Benedict W. J. Irwin, Jul 11 2018
a(n) = Sum_{p|n} p*mu(n/p), where p is prime. - Ridouane Oudra, Nov 12 2019

Extensions

More terms from R. J. Mathar, May 23 2008

A156833 A054525 * A156348 * [1,2,3,...].

Original entry on oeis.org

1, 2, 3, 6, 5, 16, 7, 24, 24, 38, 11, 103, 13, 68, 127, 144, 17, 261, 19, 404, 291, 152, 23, 994, 370, 206, 540, 1093, 29, 2195, 31, 1584, 943, 338, 2543, 4808, 37, 416, 1479, 7371, 41, 7929, 43, 4691, 8976, 596, 47, 18876, 6510, 11035, 3091
Offset: 1

Views

Author

Gary W. Adamson, Feb 16 2009

Keywords

Comments

Conjecture: for n>1, a(n) = n iff n is prime.
Companion to A156834: (1, 2, 3, 5, 5, 12, 7, 17, 19,...).

Examples

			a(4) = 6 since first 4 terms of A156348 * [1, 2, 3, 4,...] = (1, 3, 4, 9);
Then (1, 3, 4, 9) dot (0, -1, 0, 1) = (0 - 3 + 0 + 9) = 6. Row 4 of A054525 = (0, -1, 0, 1).
		

Crossrefs

Programs

  • Maple
    A156833T := proc(n,k)
        add(A054525(n,j)*A156348(j,k),j=k..n) ;
    end proc:
    A156833 := proc(n)
        add(A156833T(n,k)*k,k=1..n) ;
    end proc: # R. J. Mathar, Mar 03 2013
  • Mathematica
    A054525[n_, k_] := If[Divisible[n, k], MoebiusMu[n/k], 0];
    A156348[n_, k_] := Which[k < 1 || k > n, 0, Mod[n, k] == 0, Binomial[n/k - 2 + k, k - 1], True, 0];
    T[n_, k_] := Sum[A054525[n, j]*A156348[j, k], {j, k, n}];
    a[n_] := Sum[T[n, k]*k, {k, 1, n}];
    Table[a[n], {n, 1, 51}] (* Jean-François Alcover, Oct 15 2023 *)

Formula

A054525 * A156348 * [1,2,3,...]

Extensions

Extended beyond a(14) by R. J. Mathar, Mar 03 2013

A125093 Triangle T(n,k) = n*A054525(n,k) read by rows.

Original entry on oeis.org

1, -2, 2, -3, 0, 3, 0, -4, 0, 4, -5, 0, 0, 0, 5, 6, -6, -6, 0, 0, 6, -7, 0, 0, 0, 0, 0, 7, 0, 0, 0, -8, 0, 0, 0, 8, 0, 0, -9, 0, 0, 0, 0, 0, 9, 10, -10, 0, 0, -10, 0, 0, 0, 0, 10, -11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 12, 0, -12, 0, -12, 0, 0, 0, 0, 0, 12, -13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13, 14, -14, 0, 0, 0, 0, -14, 0, 0, 0, 0, 0, 0, 14, 15, 0, -15, 0
Offset: 1

Views

Author

Gary W. Adamson, Jan 22 2007

Keywords

Examples

			First few rows of the triangle are:
1;
-2, 2;
-3, 0, 3;
0, -4, 0, 4;
-5, 0, 0, 0, 5;
6, -6, -6, 0, 0, 6;
-7, 0, 0, 0, 0, 0, 7;
...
		

Crossrefs

Programs

  • Maple
    A125093 := proc(n,k) if n = k then n; elif n mod k = 0 then n*numtheory[mobius](n/k) ; else 0; end if; end proc:
    seq(seq(A125093(n,k),k=1..n),n=1..16) ; # R. J. Mathar, Apr 10 2011

Formula

T(n,1) = n*mu(n) = A055615(n).

Extensions

Offset and definition corrected by R. J. Mathar, Apr 10 2011

A127448 Triangle T(n,k) read by rows: matrix product A054525 * A127648.

Original entry on oeis.org

1, -1, 2, -1, 0, 3, 0, -2, 0, 4, -1, 0, 0, 0, 5, 1, -2, -3, 0, 0, 6, -1, 0, 0, 0, 0, 0, 7, 0, 0, 0, -4, 0, 0, 0, 8, 0, 0, -3, 0, 0, 0, 0, 0, 9, 1, -2, 0, 0, -5, 0, 0, 0, 0, 10, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 2, 0, -4, 0, -6, 0, 0, 0, 0, 0, 12, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13, 1, -2, 0, 0, 0, 0, -7, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Gary W. Adamson, Jan 14 2007

Keywords

Examples

			First few rows of the triangle are;
1;
-1, 2;
-1, 0, 3;
0, -2, 0, 4;
-1, 0, 0, 0, 5;
1, -2, -3, 0, 0, 6;
-1, 0, 0, 0, 0, 0, 7;
0, 0, 0, -4, 0, 0, 0, 8;
0, 0, -3, 0, 0, 0, 0, 0, 9;
1, -2, 0, 0,-5, 0, 0, 0, 0, 10;
...
		

Crossrefs

Programs

  • Maple
    A127648 := proc(n,k) if n = k then n; else 0 ; fi; end:
    A054525 := proc(n,k) if k = n then 1; elif n mod k = 0 then numtheory[mobius](n/k) ; else 0 ; fi; end:
    A127448 := proc(n,k) add( A054525(n,j)*A127648(j,k), j=k..n) ; end: seq(seq( A127448(n,k),k=1..n),n=1..15) ;

Formula

T(n,k) = sum _{j=k..n} A054525(n,j)*A127648(j,k) = k*A054525(n,k).
sum_{k=1..n} T(n,k) = A000010(n) (row sums).
T(n,1) = A008683(n).

Extensions

Converted comments to formulas, extended - R. J. Mathar, Sep 11 2009
Corrected A-number typo in a formula - R. J. Mathar, Sep 17 2009
Corrected last example line by John Mason, Jan 07 2015

A127638 A054525 * A127640, where A127640 = infinite lower triangular matrix with the sequence of primes in the main diagonal and the rest zeros.

Original entry on oeis.org

2, -2, 3, -2, 0, 5, 0, -3, 0, 7, -2, 0, 0, 0, 11, 2, -3, -5, 0, 0, 13, -2, 0, 0, 0, 0, 0, 17, 0, 0, 0, -7, 0, 0, 0, 19, 0, 0, -5, 0, 0, 0, 0, 0, 23, 2, -3, 0, 0, -11, 0, 0, 0, 0, 29, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 31, 0, 3, 0, -7, 0, -13, 0, 0, 0, 0, 0, 37, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 41, 2, -3, 0, 0, 0, 0, -17, 0, 0, 0, 0, 0, 0, 43, 2, 0, -5, 0, -11, 0, 0
Offset: 1

Views

Author

Gary W. Adamson, Jan 21 2007

Keywords

Comments

Right diagonal = primes: (2, 3, 5, 7, ...). Row sums = the Mobius transform of primes, A007444: (2, 1, 3, 4, 9, 7, ...).

Examples

			First few rows of the triangle:
   2;
  -2,  3;
  -2,  0,  5;
   0, -3,  0, 7;
  -2,  0,  0, 0, 11;
   2, -3, -5, 0,  0, 13;
  ...
		

Crossrefs

Programs

  • Maple
    A054525 := proc(n,k) if n mod k = 0 then numtheory[mobius](n/k) ; else 0 ; fi ; end: A127648 := proc(n,k) A054525(n,k)*ithprime(k) ; end: for n from 1 to 16 do for k from 1 to n do printf("%d,", A127648(n,k)) ; od ; od ; # R. J. Mathar, Mar 14 2007

Extensions

More terms from R. J. Mathar, Mar 14 2007
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