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.

A333019 Numbers k such that both k and k + 2 are totient numbers (A002202).

Original entry on oeis.org

2, 4, 6, 8, 10, 16, 18, 20, 22, 28, 30, 40, 42, 44, 46, 52, 54, 56, 58, 64, 70, 78, 80, 82, 100, 102, 104, 106, 108, 110, 126, 128, 130, 136, 138, 148, 160, 162, 164, 166, 176, 178, 190, 196, 198, 208, 210, 220, 222, 224, 226, 238, 250, 260, 262, 268, 270, 280
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2020

Keywords

Examples

			2 is a term since both 2 and 4 are totient numbers.

Links

Crossrefs

Cf. A000010, A002202, A005277, A063512, A083533, A333020, A333021, A333022, A333023, A333024.

Programs

  • PARI
    for(k = 1, 150, if(istotient(2*k) && istotient(2*k+2), print1(2*k,", ")))

A333020 Starts of runs of 3 consecutive even numbers that are all totient numbers (A002202).

Original entry on oeis.org

2, 4, 6, 8, 16, 18, 20, 28, 40, 42, 44, 52, 54, 56, 78, 80, 100, 102, 104, 106, 108, 126, 128, 136, 160, 162, 164, 176, 196, 208, 220, 222, 224, 260, 268, 292, 328, 342, 344, 356, 378, 380, 416, 438, 440, 460, 462, 464, 476, 498, 500, 502, 504, 520, 560, 584
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2020

Keywords

Examples

			2 is a term since 2, 4 and 6 are all totient numbers.

Links

Crossrefs

Cf. A000010, A002202, A005277, A063512, A083533, A333019, A333021, A333022, A333023, A333024.

Programs

  • PARI
    m = 3; v = vector(m); for(k=1, m, v[k] = istotient(2*k)); for(k = m+1, 300, if(Set(v) == [1], print1(2*(k-m),", ")); v = concat(v[2..m], istotient(2*k)))

A333021 Starts of runs of 4 consecutive even numbers that are all totient numbers (A002202).

Original entry on oeis.org

2, 4, 6, 16, 18, 40, 42, 52, 54, 78, 100, 102, 104, 106, 126, 160, 162, 220, 222, 342, 378, 438, 460, 462, 498, 500, 502, 856, 858, 880, 882, 1086, 1276, 1278, 1300, 1422, 1480, 1482, 1566, 1660, 1662, 1804, 1806, 1996, 2058, 2200, 2202, 2236, 2238, 3016, 3018
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2020

Keywords

Examples

			2 is a term since 2, 4, 6 and 8 are all totient numbers.

Links

Crossrefs

Cf. A000010, A002202, A005277, A063512, A083533, A333019, A333020, A333022, A333023, A333024.

Programs

  • PARI
    m = 4; v = vector(m); for(k=1, m, v[k] = istotient(2*k)); for(k = m+1, 1500, if(Set(v) == [1], print1(2*(k-m),", ")); v = concat(v[2..m], istotient(2*k)))

A333022 Starts of runs of 5 consecutive even numbers that are all totient numbers (A002202).

Original entry on oeis.org

2, 4, 16, 40, 52, 100, 102, 104, 160, 220, 460, 498, 500, 856, 880, 1276, 1480, 1660, 1804, 2200, 2236, 3016, 3160, 3460, 4516, 4780, 5500, 5920, 6040, 6196, 6820, 7240, 7636, 7696, 7720, 8536, 8620, 9196, 9460, 9880, 10456, 12916, 13756, 13960, 14416, 15640
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2020

Keywords

Examples

			2 is a term since 2, 4, 6, 8 and 10 are all totient numbers.

Links

Crossrefs

Cf. A000010, A002202, A005277, A063512, A083533, A333019, A333020, A333021, A333023, A333024.

Programs

  • PARI
    m = 5; v = vector(m); for(k=1, m, v[k] = istotient(2*k)); for(k = m+1, 7500, if(Set(v) == [1], print1(2*(k-m),", ")); v = concat(v[2..m], istotient(2*k)))

A333023 Starts of runs of 6 consecutive even numbers that are all totient numbers (A002202).

Original entry on oeis.org

2, 100, 102, 498, 267670, 26734060, 26734062, 31253680, 65974998, 70938496, 118428800, 1232747200, 2764919296, 3149734998, 3149735000, 3413655896, 3415058276, 3755544796, 4446555802, 5727840798, 6156991616, 10080661998, 10464983096, 11054945296, 11953158220
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2020

Keywords

Examples

			2 is a term since 2, 4, 6, 8, 10 and 12 are all totient numbers.

Links

Crossrefs

Cf. A000010, A002202, A005277, A063512, A083533, A333019, A333020, A333021, A333022, A333024.

Programs

  • PARI
    m = 6; v = vector(m); for(k=1, m, v[k] = istotient(2*k)); for(k = m+1, 1.5e5, if(Set(v) == [1], print1(2*(k-m),", ")); v = concat(v[2..m], istotient(2*k)))
Showing 1-5 of 5 results.

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

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