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 1-3 of 3 results.

A095290 Number of lower Wythoff primes (A095280) in range ]2^n,2^(n+1)].

Original entry on oeis.org

1, 0, 1, 3, 5, 8, 14, 30, 40, 86, 162, 289, 541, 1017, 1881, 3527, 6652, 12641, 23855, 45455, 86753, 165844, 317363, 609942, 1171377, 2253588, 4343268, 8381084, 16198859, 31329311, 60683252, 117637523, 228259189
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Crossrefs

a(n) = A036378(n)-A095291(n). Cf. A095060, A095291.

A184792 Numbers k such that floor(k*r) is prime, where r = golden ratio=(1+sqrt(5))/2.

Original entry on oeis.org

2, 7, 11, 12, 18, 23, 27, 33, 37, 38, 42, 44, 49, 60, 63, 64, 70, 79, 81, 85, 86, 101, 107, 111, 112, 122, 123, 131, 138, 142, 148, 149, 159, 163, 168, 174, 175, 190, 194, 196, 205, 215, 216, 222, 227, 231, 237, 241, 248, 253, 259, 268, 274, 278, 283, 285, 289, 301, 304, 309, 311, 315, 322, 348, 352, 353, 357, 363, 367, 372, 379, 383, 390, 398, 400, 404, 409, 416, 419, 457, 468, 478, 487, 493, 500, 508, 509, 519, 530, 531, 545, 546, 561, 568, 582, 589, 598
Offset: 1

Views

Author

Clark Kimberling, Jan 22 2011

Keywords

Examples

			The sequence L(n)=floor(n*r) begins with
1,3,4,6,8,9,11,12,14,16,17,...,
which includes the primes L(2)=3, L(7)=11,...
		

Crossrefs

Programs

  • Mathematica
    r=(1+5^(1/2))/2; s=r/(r-1);
    a[n_]:=Floor [n*r];  (* A095280 *)
    b[n_]:=Floor [n*s];  (* A095281 *)
    Table[a[n],{n,1,120}]
    t1={};Do[If[PrimeQ[a[n]], AppendTo[t1,a[n]]],{n,1,600}];t1
    t2={};Do[If[PrimeQ[a[n]], AppendTo[t2,n]],{n,1,600}];t2
    t3={};Do[If[MemberQ[t1,Prime[n]],AppendTo[t3,n]],{n,1,300}];t3
    t4={};Do[If[PrimeQ[b[n]], AppendTo[t4,b[n]]],{n,1,600}];t4
    t5={};Do[If[PrimeQ[b[n]], AppendTo[t5,n]],{n,1,600}];t5
    t6={};Do[If[MemberQ[t4,Prime[n]],AppendTo[t6,n]],{n,1,300}];t6
    (* The lists t1, t2, t3, t4, t5, t6 match the sequences
    A095280, A184792, A184793, A095281, A184794, A184795 *)
    Select[Range[600],PrimeQ[Floor[GoldenRatio #]]&] (* Harvey P. Dale, Mar 28 2024 *)

A095281 Upper Wythoff primes, i.e., primes in A001950.

Original entry on oeis.org

2, 5, 7, 13, 23, 31, 41, 47, 73, 83, 89, 107, 109, 149, 151, 157, 167, 191, 193, 227, 233, 251, 269, 277, 293, 311, 337, 353, 379, 397, 421, 431, 439, 463, 479, 523, 541, 547, 557, 599, 607, 617, 641, 659, 683, 691, 701, 709, 719, 727, 733, 743
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Contains all primes p whose Zeckendorf-expansion A014417(p) ends with an odd number of 0's.

Crossrefs

Intersection of A000040 & A001950. Complement of A095280 in A000040. Cf. A095081, A095083, A095084, A095290.

Programs

  • Python
    from math import isqrt
    from itertools import count, islice
    from sympy import isprime
    def A095281_gen(): # generator of terms
        return filter(isprime,((n+isqrt(5*n**2)>>1)+n for n in count(1)))
    A095281_list = list(islice(A095281_gen(),30)) # Chai Wah Wu, Aug 16 2022
Showing 1-3 of 3 results.