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 1-4 of 4 results.

A307993 G.f. A(x) satisfies: A(x) = x + x^2 + x^3 * (1 + A(x) + A(x^2) + A(x^3) + ...).

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 3, 3, 5, 4, 6, 7, 8, 7, 13, 9, 12, 17, 15, 13, 27, 16, 22, 32, 24, 23, 48, 27, 33, 55, 40, 34, 79, 41, 49, 87, 55, 55, 122, 56, 72, 132, 81, 73, 174, 82, 98, 196, 106, 99, 253, 110, 131, 267, 144, 132, 342, 153, 175, 359, 188, 176, 459, 189, 218, 496, 238, 229, 602
Offset: 1

Views

Author

Ilya Gutkovskiy, May 09 2019

Keywords

Comments

Shifts left 3 places under inverse Moebius transform.

Crossrefs

Programs

  • Mathematica
    terms = 69; A[] = 0; Do[A[x] = x + x^2 + x^3 (1 + Sum[A[x^k], {k, 1, terms}]) + O[x]^(terms + 1) // Normal, terms + 1]; Rest[CoefficientList[A[x], x]]
    a[n_] := a[n] = SeriesCoefficient[x + x^2 + x^3 (1 + Sum[a[k] x^k/(1 - x^k), {k, 1, n - 1}]), {x, 0, n}]; Table[a[n], {n, 1, 69}]
    a[n_] := a[n] = Sum[a[d], {d, Divisors[n - 3]}]; a[1] = a[2] = a[3] = 1; Table[a[n], {n, 1, 69}]

Formula

G.f.: x + x^2 + x^3 * (1 + Sum_{n>=1} a(n)*x^n/(1 - x^n)).
a(1) = a(2) = a(3) = 1; a(n+3) = Sum_{d|n} a(d).

A307994 G.f. A(x) satisfies: A(x) = x + x^2 + x^3 + x^4 * (1 + A(x) + A(x^2) + A(x^3) + ...).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 3, 2, 5, 3, 6, 4, 8, 4, 12, 5, 12, 7, 18, 6, 19, 8, 27, 10, 24, 9, 42, 12, 30, 13, 55, 13, 45, 14, 73, 18, 52, 18, 99, 19, 61, 24, 129, 20, 82, 25, 154, 29, 92, 26, 208, 32, 110, 33, 239, 33, 138, 38, 297, 42, 152, 39, 367, 43, 167, 51, 440, 49, 207, 52, 493, 59, 239
Offset: 1

Views

Author

Ilya Gutkovskiy, May 09 2019

Keywords

Comments

Shifts left 4 places under inverse Moebius transform.

Crossrefs

Programs

  • Mathematica
    terms = 74; A[] = 0; Do[A[x] = x + x^2 + x^3 + x^4 (1 + Sum[A[x^k], {k, 1, terms}]) + O[x]^(terms + 1) // Normal, terms + 1]; Rest[CoefficientList[A[x], x]]
    a[n_] := a[n] = SeriesCoefficient[x + x^2 + x^3 + x^4 (1 + Sum[a[k] x^k/(1 - x^k), {k, 1, n - 1}]), {x, 0, n}]; Table[a[n], {n, 1, 74}]
    a[n_] := a[n] = Sum[a[d], {d, Divisors[n - 4]}]; a[1] = a[2] = a[3] = a[4] = 1; Table[a[n], {n, 1, 74}]

Formula

G.f.: x + x^2 + x^3 + x^4 * (1 + Sum_{n>=1} a(n)*x^n/(1 - x^n)).
a(1) = ... = a(4) = 1; a(n+4) = Sum_{d|n} a(d).

A308083 G.f. A(x) satisfies: A(x) = x + x^2 + x^3 + x^4 + x^5 * (1 + Sum_{i>=1} Sum_{j>=1} A(x^(i*j))).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 3, 3, 6, 3, 9, 5, 12, 11, 11, 11, 22, 14, 23, 19, 29, 24, 41, 25, 40, 41, 48, 43, 66, 45, 71, 67, 86, 68, 95, 73, 113, 110, 118, 107, 157, 115, 162, 148, 182, 159, 225, 164, 235, 229, 247, 227, 296, 244, 328, 297, 357, 298, 413, 352, 452, 409, 436, 415, 575
Offset: 1

Views

Author

Ilya Gutkovskiy, May 11 2019

Keywords

Comments

Shifts 5 places left when inverse Moebius transform applied twice.

Crossrefs

Programs

  • Mathematica
    a[n_] := a[n] = Sum[DivisorSigma[0, (n - 5)/d] a[d], {d, Divisors[n - 5]}]; a[1] = a[2] = a[3] = a[4] = a[5] = 1; Table[a[n], {n, 1, 65}]

Formula

a(1) = ... = a(5) = 1; a(n+5) = Sum_{d|n} tau(n/d)*a(d), where tau = number of divisors (A000005).

A343190 a(1) = ... = a(5) = 1; a(n+5) = Sum_{d|n} mu(n/d) * a(d).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1, -2, -2, -1, -2, -1, -3, -2, -2, -2, -1, -3, -3, 0, -3, 0, -3, -2, -1, -1, -1, -2, -2, 1, -1, 3, -3, -1, 2, 2, 2, -1, -2, 5, 4, 4, -2, 1, 5, 7, 6, -1, 0, 10, 7, 10, 0, 0, 9, 14, 9, 0, 2, 12, 15, 14, -1, 3, 14, 18
Offset: 1

Views

Author

Ilya Gutkovskiy, Apr 07 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[1] = a[2] = a[3] = a[4] = a[5] = 1; a[n_] := a[n] = Sum[MoebiusMu[(n - 5)/d] a[d], {d, Divisors[n - 5]}]; Table[a[n], {n, 75}]
Showing 1-4 of 4 results.