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.

A235933 Numbers coprime to 35.

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 9, 11, 12, 13, 16, 17, 18, 19, 22, 23, 24, 26, 27, 29, 31, 32, 33, 34, 36, 37, 38, 39, 41, 43, 44, 46, 47, 48, 51, 52, 53, 54, 57, 58, 59, 61, 62, 64, 66, 67, 68, 69, 71, 72, 73, 74, 76, 78, 79, 81, 82, 83, 86, 87, 88, 89, 92, 93, 94, 96, 97, 99
Offset: 1

Views

Author

Oleg P. Kirillov, Jan 17 2014

Keywords

Comments

The asymptotic density of this sequence is 24/35. - Amiram Eldar, Oct 23 2020

Crossrefs

Cf. A160547 (numbers coprime to 31), A229968 (numbers coprime to 33), A204458 (numbers coprime to 34), A007310 (numbers coprime to 36).
Cf. A045572 (numbers not divisible by 5 or 2), A229829 (numbers not divisible by 5 or 3), A047201 (numbers not divisible by 5), A236207 (numbers not divisible by 5 or 11).

Programs

  • Haskell
    a235933 n = a235933_list !! (n-1)
    a235933_list = filter ((== 1) . gcd 35) [1..]
    -- Reinhard Zumkeller, Mar 27 2014
  • Magma
    [n: n in [1..100] | GCD(n,35) eq 1]; // Bruno Berselli, Mar 27 2014
    
  • Mathematica
    Select[Range[100], GCD[#, 35] == 1 &] (* Bruno Berselli, Mar 27 2014 *)
  • Sage
    [i for i in range(100) if gcd(i, 35) == 1] # Bruno Berselli, Mar 27 2014
    

Extensions

Signature corrected from Georg Fischer, Feb 07 2021
Erroneous recurrence removed from Bruno Berselli, Feb 08 2021

A229973 Numbers coprime to 39.

Original entry on oeis.org

1, 2, 4, 5, 7, 8, 10, 11, 14, 16, 17, 19, 20, 22, 23, 25, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44, 46, 47, 49, 50, 53, 55, 56, 58, 59, 61, 62, 64, 67, 68, 70, 71, 73, 74, 76, 77, 79, 80, 82, 83, 85, 86, 88, 89, 92, 94, 95, 97, 98, 100, 101, 103, 106
Offset: 1

Views

Author

Gary Detlefs, Oct 04 2013

Keywords

Comments

Numbers not divisible by 3 or 13.
For n from 1 to 24, a(n) mod 39-n - floor(11*n/25)-2*floor(n/8) has a period of 24, consisting of all zeros except a -2 at indices 8, 16, and 24.
The asymptotic density of this sequence is 8/13. - Amiram Eldar, Oct 23 2020

Crossrefs

Programs

  • Maple
    for n from 1 to 50 do if n mod 3<>0 and n mod 13<>0 then print(n) fi od
  • Mathematica
    CoefficientList[Series[(x^22 + x^20 + x^18 + x^16 + 2 x^14 - x^12 + 3 x^11 - x^10 + 2 x^8 + x^6 + x^4 + x^2 + 1)/((x - 1)^2 (x + 1) (x^2 - x + 1) (x^2 + 1) (x^4 - x^2 + 1) (x^4 + 1) (x^8 - x^4 + 1)), {x, 0, 80}], x] (* Vincenzo Librandi, Oct 08 2013 *)
    Select[Range[100], CoprimeQ[39, #] &] (* Amiram Eldar, Oct 23 2020 *)

Formula

a(n+24) = a(n) + 39.
a(n) = 39*floor((n-1)/24) + f(n) + floor(11*f(n)/25) + 2*floor(f(n)/8) - 2*floor(((n-1)mod 8)/7) + 40*floor(f(n-1)/23), where f(n) = n mod 24.
G.f.: x*(x^22+x^20+x^18+x^16+2*x^14-x^12+3*x^11-x^10+2*x^8+x^6+x^4+x^2+1) / ((x-1)^2*(x+1)*(x^2-x+1)*(x^2+1)*(x^4-x^2+1)*(x^4+1)*(x^8-x^4+1)). - Colin Barker, Oct 07 2013

Extensions

More terms from Colin Barker, Oct 07 2013
a(34) corrected by Vincenzo Librandi, Oct 08 2013

A236217 Numbers not divisible by 3, 5 or 11.

Original entry on oeis.org

1, 2, 4, 7, 8, 13, 14, 16, 17, 19, 23, 26, 28, 29, 31, 32, 34, 37, 38, 41, 43, 46, 47, 49, 52, 53, 56, 58, 59, 61, 62, 64, 67, 68, 71, 73, 74, 76, 79, 82, 83, 86, 89, 91, 92, 94, 97, 98, 101, 103, 104, 106, 107, 109, 112, 113, 116, 118, 119, 122, 124, 127, 128
Offset: 1

Views

Author

Oleg P. Kirillov, Jan 20 2014

Keywords

Comments

Numbers coprime to 165. The asymptotic density of this sequence is 16/33. - Amiram Eldar, Oct 23 2020

Crossrefs

Intersection of: A160542 and A229829; A047201 and A229968; A001651, A047201 and A160542.

Programs

  • Mathematica
    Select[Range[200], Mod[#, 3] > 0 && Mod[#, 5] > 0 && Mod[#, 11] > 0 &] (* or *) Select[Range[200], Or @@ Divisible[#, {3, 5, 11}] == False &] (* Bruno Berselli, Mar 24 2014 *)
    Select[Range[130], CoprimeQ[165, #] &] (* Amiram Eldar, Oct 23 2020 *)

Formula

a(n) = a(n-1) + a(n-80) - a(n-81) for n > 81. - Bruno Berselli, Mar 25 2014

A230193 Numbers divisible by 3 or 11.

Original entry on oeis.org

3, 6, 9, 11, 12, 15, 18, 21, 22, 24, 27, 30, 33, 36, 39, 42, 44, 45, 48, 51, 54, 55, 57, 60, 63, 66, 69, 72, 75, 77, 78, 81, 84, 87, 88, 90, 93, 96, 99, 102, 105, 108, 110, 111, 114, 117, 120, 121, 123, 126, 129, 132, 135, 138, 141, 143, 144, 147, 150, 153
Offset: 1

Views

Author

Gary Detlefs, Oct 11 2013

Keywords

Comments

In general, sequences of numbers divisible by primes p and q have the form a(n+p+q-1) = a(n) + p*q.
Union of A008585 and A008593 (0 excluded). - Michel Marcus, Oct 16 2013
The asymptotic density of this sequence is 13/33. - Amiram Eldar, Mar 25 2021

Crossrefs

Complement of A229968.

Programs

  • Maple
    for n from 1 to 53 do if n mod 3 = 0 and n mod 11 = 0 then print(n) fi od
  • Mathematica
    Select[Range[200], GCD[#, 33] > 1 &] (* T. D. Noe, Oct 15 2013 *)

Formula

a(n+13) = a(n) + 33.
Showing 1-4 of 4 results.