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 1-9 of 9 results.

A173603 a(1) = 1, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = a(n-1) + 2.

Original entry on oeis.org

1, 4, 12, 192, 237684487542793012780631851008
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173604, A173605, A173606, A173607, A173608, A173609, A171959, A173011.

Formula

A000005(a(n)) = a(n-1) + 2 for n >= 2.

A173605 a(1) = 1, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = a(n-1) + 4.

Original entry on oeis.org

1, 16, 240, 17293822569102704640
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173603, A173604, A173606, A173607, A173608, A173609, A171959, A173011.

Formula

A000005(a(n)) = a(n-1) + 4 for n >= 2.

A173011 a(1) = 0, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = a(n-1) + 4.

Original entry on oeis.org

0, 6, 48, 61440
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173603, A173604, A173605, A173606, A173607, A173608, A173609, A171959.

Formula

A000005(a(n)) = a(n-1) + 4 for n >= 2.

A173604 a(1) = 1, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = a(n-1) + 3.

Original entry on oeis.org

1, 6, 36, 36864
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173603, A173605, A173606, A173607, A173608, A173609, A171959, A173011.

Formula

A000005(a(n)) = a(n-1) + 3 for n >= 2.

A173606 a(1) = 1, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = 2 * a(n-1).

Original entry on oeis.org

1, 2, 6, 60, 55440
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173603, A173604, A173605, A173607, A173608, A173609, A171959, A173011.

Formula

A000005(a(n)) = 2 * a(n-1) for n >= 2.

A173607 a(1) = 1, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = 3 * a(n-1).

Original entry on oeis.org

1, 4, 60, 277200
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173603, A173604, A173605, A173606, A173608, A173609, A171959, A173011.

Formula

A000005(a(n)) = 3 * a(n-1) for n >= 2.

A173608 a(1) = 1, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = 4 * a(n-1).

Original entry on oeis.org

1, 6, 360, 1102701600
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173603, A173604, A173605, A173606, A173607, A173609, A171959, A173011.

Formula

A000005(a(n)) = 4 * a(n-1) for n >= 2.

A173609 a(1) = 0, for n >= 2; a(n) = the smallest number h such that tau(h) = A000005(h) = a(n-1) + 2.

Original entry on oeis.org

0, 2, 6, 24, 12288
Offset: 1

Views

Author

Jaroslav Krizek, Nov 06 2010

Keywords

Comments

The next term is too large to include.

Crossrefs

Cf. A014221, A173603, A173604, A173605, A173606, A173607, A173608, A171959, A173011.

Formula

A000005(a(n)) = a(n-1) + 2 for n >= 2.

A219037 Numbers k such that k divides 2^k + 2 and (k-1) divides 2^k + 1.

Original entry on oeis.org

2, 6, 66, 73786976294838206466
Offset: 1

Views

Author

Max Alekseyev, Nov 10 2012

Keywords

Comments

Also, numbers k such that 2^k == k-2 (mod k*(k-1)).
The sequence is infinite: if m is in this sequence, then so is 2^m + 2.
No other terms below 10^20.

References

  • W. Sierpinski, 250 Problems in Elementary Number Theory. New York: American Elsevier, 1970. Problem #18.

Links

Crossrefs

Intersection of A006517 and A055685.
Cf. A217468, A216822, A171959.

Formula

Conjecture: a(n+1) = 2^a(n) + 2 for all n.
Showing 1-9 of 9 results.

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