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.

Previous Showing 11-20 of 20 results.

A018676 Divisors of 840.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 105, 120, 140, 168, 210, 280, 420, 840
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Comments

840 is a highly composite number: A002182(15)=840. - Reinhard Zumkeller, Jun 21 2010

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A178877, A178878, A165412, A178858, A178859, A178860, A178861, A178862, A178863, A178864.

Programs

A178858 Divisors of 5040.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 28, 30, 35, 36, 40, 42, 45, 48, 56, 60, 63, 70, 72, 80, 84, 90, 105, 112, 120, 126, 140, 144, 168, 180, 210, 240, 252, 280, 315, 336, 360, 420, 504, 560, 630, 720, 840, 1008, 1260, 1680, 2520, 5040
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

5040 is a highly composite number: A002182(19)=5040;
the sequence is finite with A002183(19)=60 terms: a(60)=5040.

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178877, A178878, A165412, A178859, A178860, A178861, A178862, A178863, A178864.

Programs

A178859 Divisors of 7560.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 18, 20, 21, 24, 27, 28, 30, 35, 36, 40, 42, 45, 54, 56, 60, 63, 70, 72, 84, 90, 105, 108, 120, 126, 135, 140, 168, 180, 189, 210, 216, 252, 270, 280, 315, 360, 378, 420, 504, 540, 630, 756, 840, 945, 1080, 1260, 1512, 1890
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

7560 is a highly composite number: A002182(20)=7560.
The sequence is finite with A002183(20)=64 terms: a(64)=7560.
Its primorial factorization is 6^2 * 210 and its representing polynomial p(x) of degree 6 with x=2 is x^6 + 18x^5 + 118x^4 + 348x^3 + 457x^2 + 210x. - Carlos Eduardo Olivieri, May 02 2015

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178877, A178878, A165412, A178858, A178860, A178861, A178862, A178863, A178864.

Programs

A178860 Divisors of 10080.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 28, 30, 32, 35, 36, 40, 42, 45, 48, 56, 60, 63, 70, 72, 80, 84, 90, 96, 105, 112, 120, 126, 140, 144, 160, 168, 180, 210, 224, 240, 252, 280, 288, 315, 336, 360, 420, 480, 504, 560, 630, 672, 720, 840, 1008
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

10080 is a highly composite number: A002182(21)=10080.
The sequence is finite with A002183(21)=72 terms: a(72)=10080.

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178877, A178878, A165412, A178858, A178859, A178861, A178862, A178863, A178864.

Programs

A178861 Divisors of 15120.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 27, 28, 30, 35, 36, 40, 42, 45, 48, 54, 56, 60, 63, 70, 72, 80, 84, 90, 105, 108, 112, 120, 126, 135, 140, 144, 168, 180, 189, 210, 216, 240, 252, 270, 280, 315, 336, 360, 378, 420, 432, 504, 540, 560, 630
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

15120 is a highly composite number: A002182(22)=15120;
the sequence is finite with A002183(22)=80 terms: a(80)=15120.
15120 is the smallest number with 80 divisors; 18480 is the next smallest; there are 84 such numbers less than 100,000. - Harvey P. Dale, Dec 17 2013

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178877, A178878, A165412, A178858, A178859, A178860, A178862, A178863, A178864.

Programs

A178862 Divisors of 20160.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 28, 30, 32, 35, 36, 40, 42, 45, 48, 56, 60, 63, 64, 70, 72, 80, 84, 90, 96, 105, 112, 120, 126, 140, 144, 160, 168, 180, 192, 210, 224, 240, 252, 280, 288, 315, 320, 336, 360, 420, 448, 480, 504, 560, 576
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

20160 is a highly composite number: A002182(23)=20160.
The sequence is finite with A002183(23)=84 terms: a(84)=20160.

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178877, A178878, A165412, A178858, A178859, A178860, A178861, A178863, A178864.

Programs

A178863 Divisors of 25200.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 25, 28, 30, 35, 36, 40, 42, 45, 48, 50, 56, 60, 63, 70, 72, 75, 80, 84, 90, 100, 105, 112, 120, 126, 140, 144, 150, 168, 175, 180, 200, 210, 225, 240, 252, 280, 300, 315, 336, 350, 360, 400, 420, 450, 504
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

25200 is a highly composite number: A002182(24)=25200;
the sequence is finite with A002183(24)=90 terms: a(90)=25200.

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178877, A178878, A165412, A178858, A178859, A178860, A178861, A178862, A178864.

Programs

A178877 Divisors of 1260.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 14, 15, 18, 20, 21, 28, 30, 35, 36, 42, 45, 60, 63, 70, 84, 90, 105, 126, 140, 180, 210, 252, 315, 420, 630, 1260
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

1260 is a highly composite number: A002182(16)=1260;
the sequence is finite with A002183(16)=36 terms: a(36)=1260.

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178878, A165412, A178858, A178859, A178860, A178861, A178862, A178863, A178864.

Programs

A178878 Divisors of 1680.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 16, 20, 21, 24, 28, 30, 35, 40, 42, 48, 56, 60, 70, 80, 84, 105, 112, 120, 140, 168, 210, 240, 280, 336, 420, 560, 840, 1680
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 21 2010

Keywords

Comments

1680 is a highly composite number: A002182(17)=1680;
the sequence is finite with A002183(17)=40 terms: a(40)=1680.

Links

Crossrefs

Cf. A018253, A018256, A018261, A018266, A018293, A018321, A018350, A018412, A018609, A018676, A178877, A165412, A178858, A178859, A178860, A178861, A178862, A178863, A178864.

Programs

A334139 Numbers that are equal to the LCM of their palindromic divisors.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 18, 20, 21, 22, 24, 28, 30, 33, 35, 36, 40, 42, 44, 45, 55, 56, 60, 63, 66, 70, 72, 77, 84, 88, 90, 99, 101, 105, 110, 111, 120, 121, 126, 131, 132, 140, 141, 151, 154, 161, 165, 168, 171, 180, 181, 191, 198, 202, 210
Offset: 1

Views

Author

Bernard Schott, Apr 15 2020

Keywords

Comments

These terms are the fixed points of A087999.
All the palindromes are in the sequence.
Now, if m is non-palindromic, then m is a term iff m = q_1^r_1 *...* q_i^r_i *...* q_k^r_k, where q_1 <...=2, r_i >= 1 and every divisor q_i^r_i is a palindrome; these q_i^r_i are in A084092 (see examples).
The first 40 terms, from 1 to 99, are exactly the 40 smallest divisors of 27720, hence the first 40 terms of A178864, but this sequence, which is infinite, is not a duplicate. Also, 27720 is in this sequence.

Examples

			2, 5, 131 are terms as palindromic primes.
111 = 3 * 37 is a term because 111 is a palindrome, so LCM(1,3,37,111) = 111.
27720 = 2^3 * 3^2 * 5 * 7 * 11, every 2^3=8, 3^2=9, 5, 7, 11 is a palindrome so 27720 is another term, no palindromic.

Crossrefs

Cf. A087999, A178864.
Subsequences: A002113, A002385, A062687, A084092.

Programs

  • Mathematica
    Select[Range[200], LCM @@ Select[Divisors[#], PalindromeQ] == # &] (* Amiram Eldar, Apr 15 2020 *)
  • PARI
    ispal(x) = my(d=digits(x)); d == Vecrev(d);
isok(n) = lcm(select(ispal,  divisors(n))) == n; \\ Michel Marcus, Apr 16 2020
Previous Showing 11-20 of 20 results.

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

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