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 1-4 of 4 results.

A210465 Let p_(3,1)(m) be the m-th prime == 1(mod 3). Then a(n) is the smallest p_(3,1)(m) such that the interval(p_(3,1)(m)*n, p_(3,1)(m+1)*n) contains exactly one prime == 1(mod 3).

Original entry on oeis.org

7, 13, 193, 271, 157, 193, 1297, 1741, 1231, 1033, 3541, 1447, 727, 2341, 9337, 1747, 9007, 2287, 3307, 14401, 8887, 8161, 8461, 28753, 23623, 23893, 10861, 59233, 70111, 28927, 44257, 101113, 152947, 41941, 65167, 41263, 183301, 409573, 150517, 35803, 138883, 81547, 79693
Offset: 2

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The limit of a(n) as n goes to infinity is infinity.
Conjectures: (1) If q is the nearest prime>a(n), then q-a(n)=4 or 6 and both of these cases occur infinitely many times. (2) If q-a(n)=4 then q is the lesser of twin primes.
Thus, if the conjectures are true, then there exist infinitely many triples of primes of the form {p,p+4,p+6}.

Crossrefs

Programs

  • Mathematica
    bPrime=Select[Table[Prime[n],{n,1000000}],Mod[#,3]==1&];(*A002476*)
    binarySearch[lst_,find_]:=Module[{lo=1,up=Length[lst],v},(While[lo<=up,v=Floor[(lo+up)/2];If[lst[[v]]-find==0,Return[v]];If[lst[[v]]0&]]]+offset-1]];
    z=1;(*example for "contains exactly ONE b-
    primes"*)Table[bPrime[[NestWhile[#1+1&,1,!((nextBPrime[n bPrime[[#1]],z]n bPrime[[#1+1]]))&]]],{n,2,20}]

A210467 Let p_(3,2)(m) be the m-th prime == 2(mod 3). Then a(n) is the smallest p_(3,2)(m) such that the interval(p_(3,2)(m)*n, p_(3,2)(m+1)*n) contains exactly one prime == 2 (mod 3).

Original entry on oeis.org

2, 2, 101, 263, 1097, 251, 311, 461, 641, 941, 1601, 2351, 2543, 5003, 2837, 4787, 5711, 4283, 7901, 10331, 8831, 2687, 7877, 54287, 5711, 5501, 5303, 56087, 69827, 15641, 63611, 138581, 106427, 91571, 69827, 266177, 142421, 177533, 179687, 309311, 55691, 119291, 509543, 593987, 1393913
Offset: 2

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Author

Keywords

Comments

The limit of a(n) as n goes to infinity is infinity.
Conjectures: (1) If q is the nearest prime > a(n), then q-a(n) = 2 or 6 and both of these cases occur infinitely many times. (2) If q-a(n) = 2, then also q is lesser of a pair of cousin primes q and q+4, see A023200.
Thus, if the conjectures are true, then there exist infinitely many triples of primes of the form {p,p+2,p+6}.

Crossrefs

Programs

  • Mathematica
    bPrime=Select[Table[Prime[n], {n, 1000000}], Mod[#, 3]==2&];
    binarySearch[lst_, find_]:=Module[{lo=2, up=Length[lst], v}, (While[lo<=up, v=Floor[(lo+up)/2]; If[lst[[v]]-find==0, Return[v]]; If[lst[[v]]0&]]]+offset-1]];
    z=1; (*example for "contains exactly ONE b-
    primes"*)Table[bPrime[[NestWhile[#1+1&, 1, !((nextBPrime[n bPrime[[#1]], z]n bPrime[[#1+1]]))&]]], {n, 2, 20}]

A210475 Let p_(4,1)(m) be the m-th prime == 1 (mod 4). Then a(n) is the smallest p_(4,1)(m) such that the interval(p_(4,1)(m)*n, p_(4,1)(m+1)*n) contains exactly one prime == 1 (mod 4).

Original entry on oeis.org

13, 13, 29, 13, 193, 97, 97, 277, 457, 1193, 109, 229, 937, 397, 349, 1597, 2137, 937, 5569, 5737, 2833, 1549, 6733, 7477, 5077, 3457, 877, 4153, 12277, 11113, 8689, 14029, 11113, 5233, 24109, 14737, 26713, 1297, 77797, 12097, 51577, 57973, 33409, 30493, 49429, 112237, 10333, 143137
Offset: 2

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Comments

The limit of a(n) as n goes to infinity is infinity.
Conjecture: for n >= 12, every a(n) is the lesser of a pair of cousin primes p and p+4, (see A023200).

Crossrefs

Programs

  • Mathematica
    myPrime=Select[Table[Prime[n],{n,3000000}],Mod[#,4]==1&];
    binarySearch[lst_,find_]:=Module[{lo=1,up=Length[lst],v},(While[lo<=up,v=Floor[(lo+up)/2];If[lst[[v]]-find==0,Return[v]];If[lst[[v]]0&]]]+offset-1]];
    z=1;(*contains exactly ONE myPrime in the interval*)
    Table[myPrime[[NestWhile[#1+1&,1,!((nextMyPrime[n myPrime[[#1]],z+1]>n myPrime[[#1+1]]))&]]],{n,2,30}]

A210476 Let p_(4,3)(m) be the m-th prime == 3 (mod 4). Then a(n) is the smallest p_(4,3)(m) such that the interval(p_(4,3)(m)*n, p_(4,3)(m+1)*n) contains exactly one prime == 3(mod 4).

Original entry on oeis.org

7, 67, 43, 67, 67, 191, 883, 43, 643, 379, 739, 103, 463, 643, 487, 883, 1303, 3847, 1447, 13963, 1087, 8863, 1999, 8167, 7687, 8443, 2707, 2203, 11083, 3463, 7687, 31387, 8419, 15919, 12979, 10099, 26683, 22027, 46687, 79687, 15439, 65839, 46723, 44683, 14887, 58963, 13879, 26947, 77587
Offset: 2

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Author

Keywords

Comments

The limit of a(n) as n goes to infinity is infinity.
Conjecture: every a(n), except for a(7) = 191, is the lesser of a pair of cousin primes p and p+4, (see A023200).

Crossrefs

Programs

  • Mathematica
    myPrime=Select[Table[Prime[n],{n,3000000}],Mod[#,4]==3&];
    binarySearch[lst_,find_]:=Module[{lo=1,up=Length[lst],v},(While[lo<=up,v=Floor[(lo+up)/2];If[lst[[v]]-find==0,Return[v]];If[lst[[v]]0&]]]+offset-1]];
    z=1;(*contains exactly ONE myPrime in the interval*)
    Table[myPrime[[NestWhile[#1+1&,1,!((nextMyPrime[n myPrime[[#1]],z+1]>n myPrime[[#1+1]]))&]]],{n,2,30}]
Showing 1-4 of 4 results.