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 1-8 of 8 results.

A057952 Number of prime factors of 9^n - 1 (counted with multiplicity).

Original entry on oeis.org

3, 5, 5, 7, 6, 8, 5, 10, 8, 10, 7, 11, 5, 9, 11, 12, 8, 12, 7, 13, 11, 11, 6, 17, 10, 9, 13, 13, 9, 17, 8, 14, 12, 12, 11, 16, 8, 11, 15, 18, 8, 18, 6, 16, 19, 10, 10, 21, 12, 18, 15, 13, 8, 18, 15, 19, 15, 13, 7, 24, 7, 13, 19, 16, 12, 18, 8, 17, 15, 20, 9, 24, 9, 13, 22, 17, 13, 22
Offset: 1

Views

Author

Patrick De Geest, Nov 15 2000

Keywords

Links

Crossrefs

bigomega(b^n-1): A046051 (b=2), A057958 (b=3), A057957 (b=4), A057956 (b=5), A057955 (b=6), A057954 (b=7), A057953 (b=8), this sequence (b=9), A057951 (b=10), A366682 (b=11), A366708 (b=12).
Cf. A001222, A002591, A024101, A074477, A085034, A133801, A274909, A366660, A366661, A366662.

Programs

  • Mathematica
    PrimeOmega[Table[9^n - 1, {n, 1, 30}]] (* Amiram Eldar, Feb 02 2020 *)

Formula

Mobius transform of A085034. - T. D. Noe, Jun 19 2003
a(n) = A001222(A024101(n)) = A057958(2*n). - Amiram Eldar, Feb 02 2020
a(n) = A057941(n) + A057958(n). - Max Alekseyev, Jan 07 2024

A366709 Number of divisors of 12^n-1.

Original entry on oeis.org

2, 4, 4, 16, 4, 32, 8, 64, 16, 16, 12, 256, 8, 64, 64, 512, 8, 512, 4, 192, 32, 48, 16, 4096, 16, 192, 64, 1024, 32, 8192, 32, 2048, 192, 64, 512, 16384, 8, 64, 128, 12288, 16, 12288, 32, 3072, 4096, 256, 8, 262144, 32, 1024, 64, 6144, 128, 65536, 192, 8192
Offset: 1

Views

Author

Sean A. Irvine, Oct 17 2023

Keywords

Examples

			a(3)=4 because 12^3-1 has divisors {1, 11, 157, 1727}.

Links

Crossrefs

Cf. A000005, A024140, A046801, A070528, A366707, A366708, A366710, A366683.

Programs

  • Maple
    a:=n->numtheory[tau](12^n-1):
seq(a(n), n=1..100);
  • Mathematica
    DivisorSigma[0, 12^Range[100]-1]
  • PARI
    a(n) = numdiv(12^n-1);

Formula

a(n) = sigma0(12^n-1) = A000005(A024140(n)).

A366707 Number of distinct prime divisors of 12^n - 1.

Original entry on oeis.org

1, 2, 2, 4, 2, 5, 3, 6, 4, 4, 3, 8, 3, 6, 6, 9, 3, 9, 2, 7, 5, 5, 4, 12, 4, 7, 6, 10, 5, 13, 5, 11, 7, 6, 9, 14, 3, 6, 7, 13, 4, 13, 5, 11, 12, 8, 3, 18, 5, 10, 6, 12, 7, 16, 7, 13, 7, 8, 4, 18, 4, 8, 8, 13, 8, 16, 5, 10, 7, 14, 4, 21, 3, 7, 11, 11, 10, 17, 4
Offset: 1

Views

Author

Sean A. Irvine, Oct 17 2023

Keywords

Links

Crossrefs

Cf. A024140, A001221, A046800, A133801, A102347, A250288, A252170, A366708, A366709, A366681.

Programs

  • PARI
    for(n = 1, 100, print1(omega(12^n - 1), ", "))

Formula

a(n) = omega(12^n-1) = A001221(A024140(n)).

A366710 Sum of the divisors of 12^n-1.

Original entry on oeis.org

12, 168, 1896, 30240, 271464, 4247040, 39156480, 636854400, 5817876000, 72749094432, 852203639280, 15743437516800, 116720110574544, 1518251476008960, 17220536137159296, 292933954031846400, 2420303924088730368, 38936041113123840000, 348523635677043192936
Offset: 1

Views

Author

Sean A. Irvine, Oct 17 2023

Keywords

Examples

			a(3)=1896 because 12^3-1 has divisors {1, 11, 157, 1727}.

Links

Crossrefs

Cf. A024140, A000203, A366707, A366708, A366709, A366711, A366684.

Programs

  • Maple
    a:=n->numtheory[sigma](12^n-1):
seq(a(n), n=1..100);
  • Mathematica
    DivisorSigma[1, 12^Range[30]-1]

Formula

a(n) = sigma(12^n-1) = A000203(A024140(n)).

A366711 a(n) = phi(12^n-1), where phi is Euler's totient function (A000010).

Original entry on oeis.org

10, 120, 1560, 13440, 226200, 2021760, 32518360, 274391040, 4534807680, 51953616000, 646094232960, 4662793175040, 97266341877120, 1070382142166400, 13666309113600000, 109897747141754880, 2016918439151095000, 17518491733377024000, 290436363064202660760
Offset: 1

Views

Author

Sean A. Irvine, Oct 17 2023

Keywords

Links

Crossrefs

phi(k^n-1): A053287 (k=2), A295500 (k=3), A295501 (k=4), A295502 (k=5), A366623 (k=6), A366635 (k=7), A366654 (k=8), A366663 (k=9), A295503 (k=10), A366685 (k=11), this sequence (k=12).
Cf. A000010, A024140, A366707, A366708, A366709, A366710, A366717, A366718.

Programs

  • Mathematica
    EulerPhi[12^Range[30] - 1]
  • PARI
    {a(n) = eulerphi(12^n-1)}

A366713 Number of prime factors of 12^n + 1 (counted with multiplicity).

Original entry on oeis.org

1, 1, 2, 3, 2, 2, 3, 3, 3, 5, 4, 2, 4, 5, 4, 7, 2, 3, 5, 4, 6, 9, 6, 4, 6, 6, 5, 10, 3, 3, 6, 3, 2, 9, 4, 5, 7, 4, 5, 11, 4, 5, 6, 5, 4, 12, 3, 5, 5, 5, 10, 9, 5, 5, 10, 7, 9, 11, 8, 6, 10, 5, 6, 15, 5, 9, 11, 4, 5, 12, 10, 3, 10, 5, 8, 17, 5, 6, 9, 4, 6, 15
Offset: 0

Views

Author

Sean A. Irvine, Oct 17 2023

Keywords

Links

Crossrefs

Cf. A178248, A001222, A054992, A057934, A057935, A057936, A057937, A057938, A057939, A057940, A057941, A366712, A366714, A366715, A366716, A366719, A366720, A366708, A366687.

Programs

  • Mathematica
    PrimeOmega[12^Range[70]+1]
  • PARI
    a(n)=bigomega(12^n+1)

Formula

a(n) = bigomega(12^n+1) = A001222(A178248(n)).

A366682 Number of prime factors of 11^n - 1 (counted with multiplicity).

Original entry on oeis.org

2, 5, 4, 7, 4, 9, 4, 9, 5, 8, 4, 13, 4, 8, 7, 12, 3, 12, 3, 11, 10, 11, 5, 17, 8, 10, 6, 13, 4, 15, 5, 15, 9, 9, 8, 17, 6, 10, 12, 15, 9, 17, 4, 15, 9, 12, 5, 24, 7, 14, 9, 13, 6, 16, 10, 19, 8, 10, 5, 21, 5, 12, 16, 19, 8, 22, 6, 15, 10, 19, 7, 24, 3, 11, 15
Offset: 1

Views

Author

Sean A. Irvine, Oct 16 2023

Keywords

Links

Crossrefs

Cf. A024127, A001222, A366681, A366683, A366684, A366685, A366687.
Cf. A046051, A057958, A057957, A057956, A057955, A057954, A057953, A057952, A057951, A366708.

Programs

  • Mathematica
    PrimeOmega[11^Range[70]-1]
  • PARI
    a(n)=bigomega(11^n-1)

Formula

a(n) = bigomega(11^n-1) = A001222(A024127(n)).

A366718 Largest prime factor of 12^n - 1.

Original entry on oeis.org

11, 13, 157, 29, 22621, 157, 4943, 233, 80749, 22621, 266981089, 20593, 20369233, 13063, 22621, 260753, 74876782031, 80749, 29043636306420266077, 85403261, 8177824843189, 57154490053, 321218438243, 2227777, 12629757106815551, 20369233, 86769286104133
Offset: 1

Views

Author

Sean A. Irvine, Oct 17 2023

Keywords

Links

Crossrefs

Cf. A024140, A006530, A005420, A074477, A274906, A074479, A274907, A074249, A274908, A274909, A005422, A274910, A366707, A366708, A366709, A366710, A366711, A366717, A366720.

Programs

  • Magma
    [Maximum(PrimeDivisors(12^n-1)): n in [1..40]];
  • Mathematica
    Table[FactorInteger[12^n - 1][[-1, 1]], {n, 40}]

Formula

a(n) = A006530(A024140(n)).
Showing 1-8 of 8 results.

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