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 1-10 of 76 results. Next

A117563 a(n) = A118534(n)/A117078(n) unless A117078(n) = 0 in which case a(n) = 0.

Original entry on oeis.org

0, 0, 1, 0, 3, 1, 5, 3, 1, 9, 1, 3, 13, 3, 1, 1, 19, 5, 9, 23, 1, 15, 11, 9, 3, 33, 11, 35, 21, 3, 3, 5, 45, 3, 49, 5, 1, 3, 23, 1, 59, 9, 63, 27, 65, 11, 1, 3, 75, 45, 1, 79, 21, 35, 1, 1, 89, 5, 39, 93, 21, 9, 3, 103, 3, 3, 25, 3, 115, 69, 1, 39, 19, 1, 75, 29, 3, 3, 3, 21, 139, 3, 143, 61, 87
Offset: 1

Views

Author

Rémi Eismann, Apr 29 2006, Feb 14 2008

Keywords

Comments

a(n) is the "level" of prime(n).
There is a unique decomposition of the primes: provided the level a(n) is > 0, we have prime(n) = weight * level + gap, or A000040(n)=A117078(n)*a(n)+A001223(n).
a(n) = 0 only for primes 2, 3 and 7.
A118534(n) = prime(n) - g(n) or A000040(n) - A001223(n) if prime(n) - g(n) > g(n), 0 otherwise.

Examples

			a(7)=15/3=5; a(14)=39/13=3; a(16)=47/47=1; a(18)=55/11=5; a(29)=105/5=11.
		

Crossrefs

Programs

  • Mathematica
    a34[n_] := If[n == 1 || n == 2 || n == 4, 0, 2 Prime[n] - Prime[n+1]];
    a78[n_] := Block[{a, p = Prime[n], np = Prime[n+1]}, a = Min[Select[ Divisors[2p - np], # > np - p& ]]; If[a == Infinity, 0, a]];
    a[n_] := If[a78[n] == 0, 0, a34[n]/a78[n]];
    Array[a, 85] (* Jean-François Alcover, Nov 02 2018, after Robert G. Wilson v in A118534  *)

Extensions

More terms from Robert G. Wilson v, May 05 2006
Edited by N. J. A. Sloane, May 14 2006

A118922 Primes for which the weight as defined in A117078 is 9 and the gap as defined in A001223 is 8.

Original entry on oeis.org

89, 359, 449, 683, 701, 719, 1439, 1979, 2213, 2609, 2663, 2699, 2843, 2879, 3041, 3221, 3491, 4751, 5399, 5813, 6029, 6389, 6983, 7019, 7919, 8171, 8369, 8513, 9539, 10151, 10169, 10259, 10313, 10781, 10979, 11321, 11519, 11681, 12149, 12203
Offset: 1

Views

Author

Rémi Eismann, May 25 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (18i-1) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			a(1) = 89 because of prime(25) = prime(24) + (prime(24)mod 9) = 97
g(n) = 8
		

Crossrefs

A118924 Primes for which the weight as defined in A117078 is 53 and the gap as defined in A001223 is 52.

Original entry on oeis.org

19609, 547171, 3099757, 3282289, 3401221, 4286851, 4648099, 5544859, 5622769, 5731207, 5868901, 6387559, 6581857, 6949147, 6985081, 7382899, 7412791, 7675141, 7697401, 8203021, 8366791, 9190411, 9649921, 9990499, 9994951
Offset: 1

Views

Author

Rémi Eismann, May 25 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (106i-1) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			Prime(2226) = prime(2225) + (prime(2225) mod 53) = 19609 + (19609 mod 53) = 19661
g(n) = 19661 - 19609 = 53 - 1 = 52
		

Crossrefs

A118359 Primes for which the weight as defined in A117078 is 7 and the gap as defined in A001223 is 6.

Original entry on oeis.org

83, 167, 251, 433, 503, 587, 601, 727, 1063, 1217, 1231, 1553, 1777, 1861, 1973, 1987, 2281, 2351, 2393, 2897, 3541, 4073, 4283, 4451, 4507, 4591, 4871, 5081, 5431, 5557, 5641, 5683
Offset: 1

Views

Author

Rémi Eismann, May 24 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (14i-1) with i=(level(n)+1)/2, level(n) defined in A117563. level(n) is not multiple of 3.

Examples

			prime(24) = prime (23) + prime(23)mod(7) = prime (23) + prime(23)mod(77)
89 = 83 + 83mod(7) = 83 + 83mod(77)
k=7, level = 77/7 = 11
		

Crossrefs

A119504 Primes for which the weight as defined in A117078 is 23.

Original entry on oeis.org

631, 773, 2467, 2833, 3121, 3203, 3347, 3617, 4219, 4733, 4909, 4951, 5273, 6619, 7027, 7129, 7529, 8263, 8783, 9049, 9413, 9643, 9649, 10891, 11483, 11719, 12541, 13093, 13183, 13841, 14243, 14293, 14851, 15121, 15629, 15667, 15671, 15761
Offset: 1

Views

Author

Rémi Eismann, May 27 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (56i-23+gap) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			a(1) = prime(115) = 631 because prime(116) = prime(115) + (prime(115) mod 53) = 641
g(n) = 641 - 631 = 10
Prime(115) + 23 - 10 = 644, 644/46 = 14
		

Crossrefs

Formula

A117078 : a(n) = smallest k such that prime(n+1) = prime(n) + (prime(n) mod k), or 0 if no such k exists. prime(n) for which k=23.

A119595 Primes for which the weight as defined in A117078 is 15 and the gap as defined in A001223 is 8.

Original entry on oeis.org

743, 1193, 1523, 1733, 2003, 2243, 2273, 3623, 4583, 4943, 5573, 5693, 6143, 6203, 6473, 7673, 8573, 8933, 9803, 10103, 11243, 11813, 12413, 12503, 13163, 14423, 14843, 15053, 15233, 15383, 16103
Offset: 1

Views

Author

Rémi Eismann, Jun 01 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (30i-7) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			a(1)=743 because of 751=743+mod(743;15) and g(n)=751-743=8
30*((49+1)/2)-7=743
a(2)=1193 because of 1201=1193+mod(1193;15) and g(n)=1201-1193=8
30*((79+1)/2)-7=1193
		

Crossrefs

A119596 Primes for which the weight as defined in A117078 is 11 and the gap as defined in A001223 is 10.

Original entry on oeis.org

241, 1627, 2089, 4201, 4663, 4861, 5323, 6247, 6379, 6709, 8821, 9283, 9679, 10141, 12253, 12517, 12781, 13441, 15091, 15289, 15619, 17599, 17929, 19249, 19447, 19843, 21757, 23539, 26839, 28687, 33703, 34429, 34693, 35089, 35353, 36343
Offset: 1

Views

Author

Rémi Eismann, Jun 01 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (22i-1) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			a(1)=241 because of 251=241+mod(241;11) and 251-241=10.
22*((21+1)/2)-1=241, level=21
a(2)=1627 because of 1637=1627+mod(1627;11) and 1637-1627=10
22*((147+1)/2)-1=1627, level=147
		

Crossrefs

A119597 Primes for which the weight as defined in A117078 is 11 and the gap as defined in A001223 is 6.

Original entry on oeis.org

61, 677, 941, 1117, 1601, 2063, 2371, 3691, 3911, 4021, 5297, 5407, 6067, 6353, 6991, 7541, 7717, 8311, 8641, 8663, 9103, 9851, 10973, 11897, 12491, 12953, 13591, 13613, 13723, 14537, 15131, 15263, 15307, 15461, 15901, 16363
Offset: 1

Views

Author

Rémi Eismann, Jun 01 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (22i-5) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			a(1)=61 because of 67=61+mod(61;11) and 67-61=6.
22*((5+1)/2)-5=61, level=5
a(2)=677 because of 683=677+mod(677;11) and 683-677=6
22*((61+1)/2)-5=677, level=5
		

Crossrefs

A118380 Primes for which the weight as defined in A117078 is 15 and the gap as defined in A001223 is 14.

Original entry on oeis.org

839, 1409, 2039, 2819, 2939, 3779, 4139, 4889, 5309, 5669, 5939, 6719, 8039, 8609, 10739, 11369, 11909, 12329, 13049, 13499, 13859, 14159, 14489, 14519, 14639, 14669
Offset: 1

Views

Author

Rémi Eismann, May 24 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (30i-1) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			Prime(147) = prime(146) + prime(146)mod(15) = 839 + 839 mod(15) = 853 839 mod (5) = 4.
		

Crossrefs

A106752 Numbers of prime factors of k, k defined in A117078.

Original entry on oeis.org

0, 0, 1, 0, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Rémi Eismann, Jun 22 2007, Feb 14 2008

Keywords

Comments

a(n) = 0 only for n = 1, 2 and 4.

Examples

			For a(1), k=0 thus a(1)=0,
For a(3), k=3 thus a(3)=1,
For a(11), k=25=5*5 thus a(11)=2.
		

Crossrefs

Formula

a(n) = numbers of factors of A117078(n). A117078(n) : smallest k such that prime(n+1) = prime(n) + (prime(n) mod k), or 0 if no such k exists.
Showing 1-10 of 76 results. Next