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 1-5 of 5 results.

A332512 Numbers k such that phi(k) == 0 (mod 12), where phi is the Euler totient function (A000010).

Original entry on oeis.org

13, 21, 26, 28, 35, 36, 37, 39, 42, 45, 52, 56, 57, 61, 63, 65, 70, 72, 73, 74, 76, 77, 78, 84, 90, 91, 93, 95, 97, 99, 104, 105, 108, 109, 111, 112, 114, 117, 119, 122, 124, 126, 129, 130, 133, 135, 140, 143, 144, 146, 147, 148, 152, 153, 154, 155, 156, 157, 161
Offset: 1

Views

Author

Amiram Eldar, Feb 14 2020

Keywords

Comments

Dence and Pomerance showed that the asymptotic number of the terms below x is ~ x.

Examples

			13 is a term since phi(13) = 12 == 0 (mod 12).
		

Crossrefs

Programs

  • Magma
    [k:k in [1..170]| EulerPhi(k) mod 12 eq 0]; // Marius A. Burtea, Feb 14 2020
  • Mathematica
    Select[Range[200], Divisible[EulerPhi[#], 12] &]

A332513 Numbers k such that phi(k) == 4 (mod 12), where phi is the Euler totient function (A000010).

Original entry on oeis.org

5, 8, 10, 12, 17, 29, 32, 34, 40, 41, 48, 53, 55, 58, 60, 75, 82, 85, 88, 89, 100, 101, 106, 110, 113, 115, 125, 128, 132, 136, 137, 145, 149, 150, 160, 170, 173, 178, 184, 187, 192, 197, 202, 204, 205, 226, 230, 232, 233, 235, 240, 250, 253, 257, 265, 269, 274
Offset: 1

Views

Author

Amiram Eldar, Feb 14 2020

Keywords

Comments

Dence and Pomerance showed that the asymptotic number of the terms below x is ~ c1 * x/sqrt(log(x)), where c1 = (sqrt(2*sqrt(3))/(3*Pi)) * c3^(-1/2) * (2*c3 + c4) = 0.6109136202..., c3 = Product_{primes p == 2 (mod 3)} (1 + 1/(p^2-1)), and c4 = Product_{primes p == 2 (mod 3)} (1 - 1/(p+1)^2).

Examples

			17 is a term since phi(17) = 16 == 4 (mod 12).
		

Crossrefs

Programs

  • Magma
    [k:k in [1..300]| EulerPhi(k) mod 12 eq 4]; // Marius A. Burtea, Feb 14 2020
  • Mathematica
    Select[Range[300], Mod[EulerPhi[#], 12] == 4 &]

A332514 Numbers k such that phi(k) == 6 (mod 12), where phi is the Euler totient function (A000010).

Original entry on oeis.org

7, 9, 14, 18, 19, 27, 31, 38, 43, 49, 54, 62, 67, 79, 81, 86, 98, 103, 127, 134, 139, 151, 158, 162, 163, 199, 206, 211, 223, 243, 254, 271, 278, 283, 302, 307, 326, 331, 343, 361, 367, 379, 398, 422, 439, 446, 463, 486, 487, 499, 523, 542, 547, 566, 571, 607, 614
Offset: 1

Views

Author

Amiram Eldar, Feb 14 2020

Keywords

Comments

Dence and Pomerance showed that the asymptotic number of the terms below x is ~ (3/8) * x/log(x).

Examples

			19 is a term since phi(19) = 18 == 6 (mod 12).
		

Crossrefs

Programs

  • Magma
    [k:k in [1..650]| EulerPhi(k) mod 12 eq 6]; // Marius A. Burtea, Feb 14 2020
  • Mathematica
    Select[Range[600], Mod[EulerPhi[#], 12] == 6 &]

A332515 Numbers k such that phi(k) == 8 (mod 12), where phi is the Euler totient function (A000010).

Original entry on oeis.org

15, 16, 20, 24, 25, 30, 33, 44, 50, 51, 64, 66, 68, 69, 80, 87, 92, 96, 102, 116, 120, 123, 138, 141, 159, 164, 165, 174, 176, 177, 188, 200, 212, 213, 220, 236, 246, 249, 255, 256, 264, 267, 272, 275, 282, 284, 289, 300, 303, 318, 320, 321, 330, 332, 339, 340
Offset: 1

Views

Author

Amiram Eldar, Feb 14 2020

Keywords

Comments

Dence and Pomerance showed that the asymptotic number of the terms below x is ~ c2 * x/sqrt(log(x)), where c2 = (sqrt(2*sqrt(3))/(3*Pi)) * c3^(-1/2) * (2*c3 - c4) = 0.3284176245..., c3 = Product_{primes p == 2 (mod 3)} (1 + 1/(p^2-1)), and c4 = Product_{primes p == 2 (mod 3)} (1 - 1/(p+1)^2).

Examples

			25 is a term since phi(25) = 20 == 8 (mod 12).
		

Crossrefs

Programs

  • Magma
    [k:k in [1..350]| EulerPhi(k) mod 12 eq 8]; // Marius A. Burtea, Feb 14 2020
  • Mathematica
    Select[Range[400], Mod[EulerPhi[#], 12] == 8 &]

A332516 Numbers k such that phi(k) == 10 (mod 12), where phi is the Euler totient function (A000010).

Original entry on oeis.org

11, 22, 23, 46, 47, 59, 71, 83, 94, 107, 118, 131, 142, 166, 167, 179, 191, 214, 227, 239, 251, 262, 263, 311, 334, 347, 358, 359, 382, 383, 419, 431, 443, 454, 467, 478, 479, 491, 502, 503, 526, 563, 587, 599, 622, 647, 659, 683, 694, 718, 719, 743, 766, 827
Offset: 1

Views

Author

Amiram Eldar, Feb 14 2020

Keywords

Comments

Dence and Pomerance showed that the asymptotic number of the terms below x is ~ (3/8) * x/log(x).

Examples

			23 is a term since phi(23) = 22 == 10 (mod 12).
		

Crossrefs

Programs

  • Magma
    [k:k in [1..850]| EulerPhi(k) mod 12 eq 10]; // Marius A. Burtea, Feb 14 2020
  • Mathematica
    Select[Range[800], Mod[EulerPhi[#], 12] == 10 &]
Showing 1-5 of 5 results.