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,", ")))

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)))

A333024 Starts of runs of 7 consecutive even numbers that are all totient numbers (A002202).

Original entry on oeis.org

100, 26734060, 3149734998, 12960114796, 15685683796, 24077884060, 36987943996, 38809984996, 62521251798, 76314338740, 319408651400
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2020

Keywords

Examples

			100 is a term since the 7 even numbers 100, 102, ... 112 are all totient numbers.

Links

Crossrefs

Cf. A000010, A002202, A005277, A063512, A083533, A333019, A333020, A333021, A333022, A333023.

Programs

  • PARI
    m = 7; v = vector(m); for(k=1, m, v[k] = istotient(2*k)); for(k = m+1, 1.5e7, if(Set(v) == [1], print1(2*(k-m),", ")); v = concat(v[2..m], istotient(2*k)))

Extensions

a(9)-a(11) from Giovanni Resta, Mar 07 2020
Showing 1-5 of 5 results.

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