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 1-9 of 9 results.

A062731 Sum of divisors of 2*n.

Original entry on oeis.org

3, 7, 12, 15, 18, 28, 24, 31, 39, 42, 36, 60, 42, 56, 72, 63, 54, 91, 60, 90, 96, 84, 72, 124, 93, 98, 120, 120, 90, 168, 96, 127, 144, 126, 144, 195, 114, 140, 168, 186, 126, 224, 132, 180, 234, 168, 144, 252, 171, 217, 216, 210, 162, 280, 216, 248, 240, 210
Offset: 1

Views

Author

Jason Earls, Jul 11 2001

Keywords

Comments

a(n) is also the total number of parts in all partitions of 2*n into equal parts. - Omar E. Pol, Feb 14 2021

Links

Crossrefs

Sigma(k*n): A000203 (k=1), A144613 (k=3), A193553 (k=4, even bisection), A283118 (k=5), A224613 (k=6), A283078 (k=7), A283122 (k=8), A283123 (k=9).
Cf. A008438, A074400, A182818, A239052 (odd bisection), A326124 (partial sums), A054784, A215947, A336923, A346870, A346878, A346880, A355750.
Row 2 of A319526. Column & Row 2 of A216626. Row 1 of A355927.
Shallow diagonal (2n,n) of A265652. See also A244658.

Programs

Formula

a(n) = A000203(2*n). - R. J. Mathar, Apr 06 2011
a(n) = A000203(n) + A054785(n). - R. J. Mathar, May 19 2020
From Vaclav Kotesovec, Aug 07 2022: (Start)
Dirichlet g.f.: zeta(s) * zeta(s-1) * (3 - 2^(1-s)).
Sum_{k=1..n} a(k) ~ 5 * Pi^2 * n^2 / 24. (End)
From Miles Wilson, Sep 30 2024: (Start)
G.f.: Sum_{k>=1} k*x^(k/gcd(k, 2))/(1 - x^(k/gcd(k, 2))).
G.f.: Sum_{k>=1} k*x^(2*k/(3 + (-1)^k))/(1 - x^(2*k/(3 + (-1)^k))). (End)

Extensions

Zero removed and offset corrected by Omar E. Pol, Jul 17 2009

A216624 Square array read by antidiagonals, T(n,k) = sum_{c|n,d|k} gcd(c,d) for n>=1, k>=1.

Original entry on oeis.org

1, 2, 2, 2, 5, 2, 3, 4, 4, 3, 2, 8, 6, 8, 2, 4, 4, 6, 6, 4, 4, 2, 10, 4, 15, 4, 10, 2, 4, 4, 12, 6, 6, 12, 4, 4, 3, 11, 4, 16, 8, 16, 4, 11, 3, 4, 6, 8, 6, 8, 8, 6, 8, 6, 4, 2, 10, 10, 22, 4, 30, 4, 22, 10, 10, 2, 6, 4, 8, 9, 8, 8, 8, 8, 9, 8, 4, 6
Offset: 1

Views

Author

Peter Luschny, Sep 12 2012

Keywords

Comments

T(n,k) = number of subgroups of C_n X C_k. [Hampjes et al.] - N. J. A. Sloane, Feb 02 2013

Examples

			[----1---2---3---4---5---6---7---8---9--10--11--12]
[ 1] 1,  2,  2,  3,  2,  4,  2,  4,  3,  4,  2,  6
[ 2] 2,  5,  4,  8,  4, 10,  4, 11,  6, 10,  4, 16
[ 3] 2,  4,  6,  6,  4, 12,  4,  8, 10,  8,  4, 18
[ 4] 3,  8,  6, 15,  6, 16,  6, 22,  9, 16,  6, 30
[ 5] 2,  4,  4,  6,  8,  8,  4,  8,  6, 16,  4, 12
[ 6] 4, 10, 12, 16,  8, 30,  8, 22, 20, 20,  8, 48
[ 7] 2,  4,  4,  6,  4,  8, 10,  8,  6,  8,  4, 12
[ 8] 4, 11,  8, 22,  8, 22,  8, 37, 12, 22,  8, 44
[ 9] 3,  6, 10,  9,  6, 20,  6, 12, 23, 12,  6, 30
[10] 4, 10,  8, 16, 16, 20,  8, 22, 12, 40,  8, 32
[11] 2,  4,  4,  6,  4,  8,  4,  8,  6,  8, 14, 12
[12] 6, 16, 18, 30, 12, 48, 12, 44, 30, 32, 12, 90
.
Displayed as a triangular array:
1,
2,  2,
2,  5,  2,
3,  4,  4,  3,
2,  8,  6,  8, 2,
4,  4,  6,  6, 4,  4,
2, 10,  4, 15, 4, 10, 2,
4,  4, 12,  6, 6, 12, 4,  4,
3, 11,  4, 16, 8, 16, 4, 11, 3,

Links

Crossrefs

Cf. A216620, A216621, A216622, A216623, A216625, A216626, A216627.
Main diagonal is A060724.
Rows give A000005, A060710, A054584, A221951, A221852.

Programs

  • Maple
    with(numtheory):
T:= (n, k)-> add(add(igcd(c,d), c=divisors(n)), d=divisors(k)):
seq(seq(T(n, 1+d-n), n=1..d), d=1..14); # Alois P. Heinz, Sep 12 2012
T:=proc(m,n) local d; add( d*tau(m*n/d^2), d in divisors(gcd(m,n))); end; # N. J. A. Sloane, Feb 02 2013
  • Mathematica
    t[n_, k_] := Sum[Sum[GCD[c, d], {c, Divisors[n]}], {d, Divisors[k]}]; Table[t[n-k+1, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, May 21 2013 *)
  • Sage
    def A216624(n, k) :
    cp = cartesian_product([divisors(n), divisors(k)])
    return reduce(lambda x,y: x+y, map(gcd, cp))
for n in (1..12): [A216624(n,k) for k in (1..12)]

Formula

T(n,n) = A060724(n) = sum_{d|n} d*tau((n/d)^2).
T(n,1) = T(1,n) = A000005(n) = tau(n).
T(n,2) = T(2,n) = A060710(n) = sum_{d|n} (3-[d is odd]) (Iverson bracket).
T(n+1,n) = A092517(n) = tau(n+1)*tau(n).
T(prime(n),1) = A007395(n) = 2.
T(prime(n),prime(n)) = A113935(n) = prime(n)+3.

A216620 Square array read by antidiagonals: T(n,k) = Sum_{c|n,d|k} phi(gcd(c,d)) for n>=1, k>=1.

Original entry on oeis.org

1, 2, 2, 2, 4, 2, 3, 4, 4, 3, 2, 6, 5, 6, 2, 4, 4, 6, 6, 4, 4, 2, 8, 4, 10, 4, 8, 2, 4, 4, 10, 6, 6, 10, 4, 4, 3, 8, 4, 12, 7, 12, 4, 8, 3, 4, 6, 8, 6, 8, 8, 6, 8, 6, 4, 2, 8, 8, 14, 4, 20, 4, 14, 8, 8, 2, 6, 4, 8, 9, 8, 8, 8, 8, 9, 8, 4, 6, 2, 12, 4, 12, 6
Offset: 1

Views

Author

Peter Luschny, Sep 12 2012

Keywords

Comments

T(n,n) = A060648(n) = Sum_{d|n} Dedekind_Psi(d).
T(n,1) = T(1,n) = A000005(n) = tau(n).
T(n,2) = T(2,n) = A062011(n) = 2*tau(n).
T(n+1,n) = A092517(n) = tau(n+1)*tau(n).
T(prime(n),1) = A007395(n) = 2.
T(prime(n),prime(n)) = A052147(n) = prime(n)+2.

Examples

			[----1---2---3---4---5---6---7---8---9--10--11--12]
[ 1] 1,  2,  2,  3,  2,  4,  2,  4,  3,  4,  2,  6
[ 2] 2,  4,  4,  6,  4,  8,  4,  8,  6,  8,  4, 12
[ 3] 2,  4,  5,  6,  4, 10,  4,  8,  8,  8,  4, 15
[ 4] 3,  6,  6, 10,  6, 12,  6, 14,  9, 12,  6, 20
[ 5] 2,  4,  4,  6,  7,  8,  4,  8,  6, 14,  4, 12
[ 6] 4,  8, 10, 12,  8, 20,  8, 16, 16, 16,  8, 30
[ 7] 2,  4,  4,  6,  4,  8,  9,  8,  6,  8,  4, 12
[ 8] 4,  8,  8, 14,  8, 16,  8, 22, 12, 16,  8, 28
[ 9] 3,  6,  8,  9,  6, 16,  6, 12, 17, 12,  6, 24
[10] 4,  8,  8, 12, 14, 16,  8, 16, 12, 28,  8, 24
[11] 2,  4,  4,  6,  4,  8,  4,  8,  6,  8, 13, 12
[12] 6, 12, 15, 20, 12, 30, 12, 28, 24, 24, 12, 50
.
Displayed as a triangular array:
   1,
   2, 2,
   2, 4,  2,
   3, 4,  4,  3,
   2, 6,  5,  6, 2,
   4, 4,  6,  6, 4,  4,
   2, 8,  4, 10, 4,  8, 2,
   4, 4, 10,  6, 6, 10, 4, 4,
   3, 8,  4, 12, 7, 12, 4, 8, 3,

Links

Crossrefs

Cf. A216621, A216622, A216623, A216624, A216625, A216626, A216627.

Programs

  • Maple
    with(numtheory):
T:= (n, k)-> add(add(phi(igcd(c,d)), c=divisors(n)), d=divisors(k)):
seq(seq(T(n, 1+d-n), n=1..d), d=1..14);  # Alois P. Heinz, Sep 12 2012
  • Mathematica
    t[n_, k_] := Outer[ EulerPhi[ GCD[#1, #2]]&, Divisors[n], Divisors[k]] // Flatten // Total; Table[ t[n-k+1, k], {n, 1, 13}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 26 2013 *)
  • Sage
    def A216620(n, k) :
    cp = cartesian_product([divisors(n), divisors(k)])
    return reduce(lambda x,y: x+y, map(euler_phi, map(gcd, cp)))
for n in (1..12): [A216620(n,k) for k in (1..12)]

A216621 Triangle read by rows, n >= 1, 1 <= k <= n, T(n,k) = Sum_{c|n,d|k} phi(gcd(c,d)).

Original entry on oeis.org

1, 2, 4, 2, 4, 5, 3, 6, 6, 10, 2, 4, 4, 6, 7, 4, 8, 10, 12, 8, 20, 2, 4, 4, 6, 4, 8, 9, 4, 8, 8, 14, 8, 16, 8, 22, 3, 6, 8, 9, 6, 16, 6, 12, 17, 4, 8, 8, 12, 14, 16, 8, 16, 12, 28, 2, 4, 4, 6, 4, 8, 4, 8, 6, 8, 13, 6, 12, 15, 20, 12, 30, 12, 28, 24, 24, 12
Offset: 1

Views

Author

Peter Luschny, Sep 12 2012

Keywords

Comments

This is the lower triangular array of A216620, which is the main entry for this sequence.
T(n,1) = A000005(n) = tau(n).
T(n,n) = A060648(n) = sum{d|n} Dedekind_Psi(d).

Examples

			The first rows of the triangle are:
  1;
  2,  4;
  2,  4,  5;
  3,  6,  6, 10;
  2,  4,  4,  6,  7;
  4,  8, 10, 12,  8, 20;
  2,  4,  4,  6,  4,  8,  9;
  4,  8,  8, 14,  8, 16,  8, 22;
  3,  6,  8,  9,  6, 16,  6, 12, 17;
  4,  8,  8, 12, 14, 16,  8, 16, 12, 28;
  2,  4,  4,  6,  4,  8,  4,  8,  6,  8, 13;

Links

Crossrefs

Cf. A216620, A216622, A216623, A216624, A216625, A216626, A216627.

Programs

  • Maple
    with(numtheory):
T:= (n, k)-> add(add(phi(igcd(c,d)), c=divisors(n)), d=divisors(k)):
seq (seq (T(n, k), k=1..n), n=1..14);  # Alois P. Heinz, Sep 12 2012
  • Mathematica
    t[n_, k_] := Sum[ EulerPhi[GCD[c, d]], {c, Divisors[n]}, {d, Divisors[k]}]; Table[t[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 28 2013 *)
  • Sage
    for n in (1..9): [A216620(n,k) for k in (1..n)]

A216622 Square array read by antidiagonals: T(n,k) = Sum_{c|n, d|k} phi(lcm(c,d)) for n >= 1, k >= 1.

Original entry on oeis.org

1, 2, 2, 3, 4, 3, 4, 6, 6, 4, 5, 8, 7, 8, 5, 6, 10, 12, 12, 10, 6, 7, 12, 15, 14, 15, 12, 7, 8, 14, 14, 20, 20, 14, 14, 8, 9, 16, 21, 24, 13, 24, 21, 16, 9, 10, 18, 24, 28, 30, 30, 28, 24, 18, 10, 11, 20, 19, 26, 35, 28, 35, 26, 19, 20, 11, 12, 22, 30, 36, 40
Offset: 1

Views

Author

Peter Luschny, Sep 12 2012

Keywords

Comments

T(n,n) = A062380(n) = Sum_{d|n} phi(d)*tau(d^2).
T(n,1) = T(1,n) = A000027(n) = n.
T(n,2) = T(2,n) = A005843(n) = 2*n.
T(n+1,n) = A002378(n) = (n+1)*n.
T(prime(n),1) = A000040(n) = prime(n).
T(prime(n),prime(n)) = 3*prime(n)-2.

Examples

			[-----1---2---3---4---5---6---7---8---9---10---11---12]
[ 1]  1,  2,  3,  4,  5,  6,  7,  8,  9,  10,  11,  12
[ 2]  2,  4,  6,  8, 10, 12, 14, 16, 18,  20,  22,  24
[ 3]  3,  6,  7, 12, 15, 14, 21, 24, 19,  30,  33,  28
[ 4]  4,  8, 12, 14, 20, 24, 28, 26, 36,  40,  44,  42
[ 5]  5, 10, 15, 20, 13, 30, 35, 40, 45,  26,  55,  60
[ 6]  6, 12, 14, 24, 30, 28, 42, 48, 38,  60,  66,  56
[ 7]  7, 14, 21, 28, 35, 42, 19, 56, 63,  70,  77,  84
[ 8]  8, 16, 24, 26, 40, 48, 56, 42, 72,  80,  88,  78
[ 9]  9, 18, 19, 36, 45, 38, 63, 72, 37,  90,  99,  76
[10] 10, 20, 30, 40, 26, 60, 70, 80, 90,  52, 110, 120
[11] 11, 22, 33, 44, 55, 66, 77, 88, 99, 110,  31, 132
[12] 12, 24, 28, 42, 60, 56, 84, 78, 76, 120, 132,  98
.
Displayed as a triangular array:
   1,
   2,  2,
   3,  4,  3,
   4,  6,  6,  4,
   5,  8,  7,  8,  5,
   6, 10, 12, 12, 10,  6,
   7, 12, 15, 14, 15, 12,  7,
   8, 14, 14, 20, 20, 14, 14,  8,
   9, 16, 21, 24, 13, 24, 21, 16,  9,

Links

Crossrefs

Cf. A216620, A216621, A216623, A216624, A216625, A216626, A216627.

Programs

  • Maple
    with(numtheory):
T:= (n, k)-> add(add(phi(ilcm(c, d)), c=divisors(n)), d=divisors(k)):
seq (seq (T(n, 1+d-n), n=1..d), d=1..14);  # Alois P. Heinz, Sep 12 2012
  • Mathematica
    t[n_, k_] := Sum[ EulerPhi[LCM[c, d]], {c, Divisors[n]}, {d, Divisors[k]}]; Table[ t[n-k+1, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 28 2013 *)
  • Sage
    def A216622(n, k) :
    cp = cartesian_product([divisors(n), divisors(k)])
    return reduce(lambda x,y: x+y, map(euler_phi, map(lcm, cp)))
for n in (1..12): [A216622(n,k) for k in (1..12)]

A216623 Triangle read by rows, n>=1, 1<=k<=n, T(n,k) = Sum_{c|n,d|k} phi(lcm(c,d)).

Original entry on oeis.org

1, 2, 4, 3, 6, 7, 4, 8, 12, 14, 5, 10, 15, 20, 13, 6, 12, 14, 24, 30, 28, 7, 14, 21, 28, 35, 42, 19, 8, 16, 24, 26, 40, 48, 56, 42, 9, 18, 19, 36, 45, 38, 63, 72, 37, 10, 20, 30, 40, 26, 60, 70, 80, 90, 52, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 31, 12, 24
Offset: 1

Views

Author

Peter Luschny, Sep 12 2012

Keywords

Comments

This is the lower triangular array of A216622, which is the main entry for this sequence.
T(n,1) = A000027(n).
T(n,n) = A062380(n).

Examples

			The first rows of the triangle are:
1,
2,  4,
3,  6,  7,
4,  8, 12, 14,
5, 10, 15, 20, 13,
6, 12, 14, 24, 30, 28,
7, 14, 21, 28, 35, 42, 19,
8, 16, 24, 26, 40, 48, 56, 42,
9, 18, 19, 36, 45, 38, 63, 72, 37,

Links

Crossrefs

Cf. A216620, A216621, A216622, A216624, A216625, A216626, A216627.

Programs

  • Maple
    with(numtheory):
T:= (n, k)-> add(add(phi(ilcm(c, d)), c=divisors(n)), d=divisors(k)):
seq (seq (T(n, k), k=1..n), n=1..14);  # Alois P. Heinz, Sep 12 2012
  • Mathematica
    t[n_, k_] := Sum[ EulerPhi[ LCM[c, d]], {c, Divisors[n]}, {d, Divisors[k]}]; Table[t[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jul 23 2013 *)
  • Sage
    # uses[A216622]
for n in (1..9): [A216622(n,k) for k in (1..n)]

A216625 Triangle read by rows, n >= 1, 1 <= k <= n, T(n,k) = Sum_{c|n,d|k} gcd(c,d).

Original entry on oeis.org

1, 2, 5, 2, 4, 6, 3, 8, 6, 15, 2, 4, 4, 6, 8, 4, 10, 12, 16, 8, 30, 2, 4, 4, 6, 4, 8, 10, 4, 11, 8, 22, 8, 22, 8, 37, 3, 6, 10, 9, 6, 20, 6, 12, 23, 4, 10, 8, 16, 16, 20, 8, 22, 12, 40, 2, 4, 4, 6, 4, 8, 4, 8, 6, 8, 14, 6, 16, 18, 30, 12, 48, 12, 44, 30, 32
Offset: 1

Views

Author

Peter Luschny, Sep 12 2012

Keywords

Comments

This is the lower triangular array of A216624, which is the main entry for this sequence.
T(n,1) = A000005(n) = tau(n).
T(n,n) = A060724(n) = Sum_{d|n} d*tau((n/d)^2).

Examples

			The first rows of the triangle are:
  1;
  2,  5;
  2,  4,  6;
  3,  8,  6, 15;
  2,  4,  4,  6,  8;
  4, 10, 12, 16,  8, 30;
  2,  4,  4,  6,  4,  8, 10;
  4, 11,  8, 22,  8, 22,  8, 37;
  3,  6, 10,  9,  6, 20,  6, 12, 23;

Links

Crossrefs

Cf. A216620, A216621, A216622, A216623, A216624, A216626, A216627.

Programs

  • Maple
    with(numtheory):
T:= (n, k)-> add(add(igcd(c, d), c=divisors(n)), d=divisors(k)):
seq (seq (T(n, k), k=1..n), n=1..14);  # Alois P. Heinz, Sep 12 2012
  • Mathematica
    T[n_, k_] := Sum[GCD[c, d], {c, Divisors[n]}, {d, Divisors[k]}]; Table[T[n, k], {n, 1, 14}, {k, 1, n}] // Flatten (* Jean-François Alcover, Mar 25 2014 *)
  • Sage
    for n in (1..9): [A216624(n,k) for k in (1..n)]

A216627 Triangle read by rows, n>=1, 1<=k<=n, T(n,k) = sum_{c|n,d|k} lcm(c,d).

Original entry on oeis.org

1, 3, 7, 4, 12, 10, 7, 15, 28, 27, 6, 18, 24, 42, 16, 12, 28, 30, 60, 72, 70, 8, 24, 32, 56, 48, 96, 22, 15, 31, 60, 51, 90, 124, 120, 83, 13, 39, 28, 91, 78, 84, 104, 195, 55, 18, 42, 72, 90, 48, 168, 144, 186, 234, 112, 12, 36, 48, 84, 72, 144, 96, 180, 156
Offset: 1

Views

Author

Peter Luschny, Sep 12 2012

Keywords

Comments

This is the lower triangular array of A216626, which is the main entry for this sequence.

Examples

			The first rows of the triangle are:
1;
3,   7;
4,  12, 10;
7,  15, 28, 27;
6,  18, 24, 42, 16;
12, 28, 30, 60, 72,  70;
8,  24, 32, 56, 48,  96,  22;
15, 31, 60, 51, 90, 124, 120,  83;
13, 39, 28, 91, 78,  84, 104, 195, 55;

Links

Crossrefs

Cf. A216620, A216621, A216622, A216623, A216624, A216625, A216626.

Programs

  • Maple
    with(numtheory):
T:= (n, k) -> add(add(ilcm(c, d), c=divisors(n)), d=divisors(k));
seq (seq (T(n, k), k=1..n), n=1..12);  # Alois P. Heinz, Sep 12 2012
  • Mathematica
    T[n_, k_] := Sum[LCM[c, d], {c, Divisors[n]}, {d, Divisors[k]}]; Table[T[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Mar 25 2014 *)
  • Sage
    for n in (1..9): [A216626(n,k) for k in (1..n)]

Formula

T(n,1) = A000203(n) = sigma(n).
T(n,n) = A064950(n) = sum_{d|n} d*tau(d^2).

A319526 Square array read by antidiagonals upwards: T(n,k) = sigma(n*k), n >= 1, k >= 1.

Original entry on oeis.org

1, 3, 3, 4, 7, 4, 7, 12, 12, 7, 6, 15, 13, 15, 6, 12, 18, 28, 28, 18, 12, 8, 28, 24, 31, 24, 28, 8, 15, 24, 39, 42, 42, 39, 24, 15, 13, 31, 32, 60, 31, 60, 32, 31, 13, 18, 39, 60, 56, 72, 72, 56, 60, 39, 18, 12, 42, 40, 63, 48, 91, 48, 63, 40, 42, 12, 28, 36, 72, 91, 90, 96, 96, 90, 91, 72, 36, 28
Offset: 1

Views

Author

Omar E. Pol, Sep 25 2018

Keywords

Examples

			The corner of the square array begins:
A000203:    1,   3,   4,   7,   6,  12,   8,  15,  13,  18,  12,  28, ...
A062731:    3,   7,  12,  15,  18,  28,  24,  31,  39,  42,  36,  60, ...
A144613:    4,  12,  13,  28,  24,  39,  32,  60,  40,  72,  48,  91, ...
A193553:    7,  15,  28,  31,  42,  60,  56,  63,  91,  90,  84, 124, ...
A283118:    6,  18,  24,  42,  31,  72,  48,  90,  78,  93,  72, 168, ...
A224613:   12,  28,  39,  60,  72,  91,  96, 124, 120, 168, 144, 195, ...
A283078:    8,  24,  32,  56,  48,  96,  57, 120, 104, 144,  96, 224, ...
A283122:   15,  31,  60,  63,  90, 124, 120, 127, 195, 186, 180, 252, ...
A283123:   13,  39,  40,  91,  78, 120, 104, 195, 121, 234, 156, 280, ...
...

Links

Crossrefs

First 9 rows (also first 9 columns) are A000203, A062731, A144613, A193553, A283118, A224613, A283078, A283122, A283123.
Main diagonal gives A065764.
Cf. A000203, A003991, A216626, A319073.

Programs

  • Mathematica
    Table[DivisorSigma[1, # k] &[m - k + 1], {m, 12}, {k, m}] // Flatten (* Michael De Vlieger, Dec 31 2018 *)

Formula

T(n,k) = A000203(n*k).
T(n,k) = A000203(A003991(n,k)).
Showing 1-9 of 9 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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