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.

A356302 The least k >= 0 such that n and A276086(n+k) are relatively prime, where A276086 is the primorial base exp-function.

Original entry on oeis.org

0, 0, 0, 3, 0, 0, 0, 0, 0, 3, 20, 0, 0, 0, 0, 15, 0, 0, 0, 0, 10, 3, 0, 0, 0, 5, 0, 3, 0, 0, 0, 0, 0, 3, 0, 175, 0, 0, 0, 3, 20, 0, 168, 0, 0, 15, 0, 0, 0, 161, 10, 3, 0, 0, 0, 5, 154, 3, 0, 0, 0, 0, 0, 147, 0, 0, 0, 0, 0, 3, 140, 0, 0, 0, 0, 15, 0, 2233, 0, 0, 10, 3, 0, 0, 126, 5, 0, 3, 0, 0, 0, 119, 0, 3, 0, 0, 0, 0, 112
Offset: 0

Views

Author

Antti Karttunen, Nov 03 2022

Keywords

Comments

For all nonzero terms, adding a(n) to n in primorial base generates at least one carry. See the formula involving A329041.

Crossrefs

Cf. A324583 (positions of zeros), A324584 (of nonzeros), A356318 (positions where a(n) > 0 and a multiple of n), A356319 (where 0 < a(n) < n).
Cf. A358213, A358214 (conjectured positions of records and their values).
Cf. also A356303, A356304.

Programs

  • PARI
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A356302(n) = { my(k=0); while(gcd(A276086(n+k),n)!=1,k++); (k); };

Formula

a(n) = A356309(n) - n.
If a(n) > 0, then A000035(a(n)) = A000035(n) and A329041(n, a(n)) > 1.

A356309 The least j >= n such that n and A276086(j) are relatively prime, where A276086 is the primorial base exp-function.

Original entry on oeis.org

0, 1, 2, 6, 4, 5, 6, 7, 8, 12, 30, 11, 12, 13, 14, 30, 16, 17, 18, 19, 30, 24, 22, 23, 24, 30, 26, 30, 28, 29, 30, 31, 32, 36, 34, 210, 36, 37, 38, 42, 60, 41, 210, 43, 44, 60, 46, 47, 48, 210, 60, 54, 52, 53, 54, 60, 210, 60, 58, 59, 60, 61, 62, 210, 64, 65, 66, 67, 68, 72, 210, 71, 72, 73, 74, 90, 76, 2310, 78
Offset: 0

Views

Author

Antti Karttunen, Nov 04 2022

Keywords

Crossrefs

Cf. A324583 (positions of the fixed points), A356314 (positions of the terms that are primorial numbers), A356316 (where a(n) is a multiple of n), A356318 (where a nontrivial multiple), A356319 (where n < a(n) < 2*n).

Programs

  • Mathematica
    f[nn_] := Block[{m = 1, i = 1, n = nn, p}, While[n > 0, p = Prime[i]; m *= p^Mod[n, p]; n = Quotient[n, p]; i++]; m]; Array[Block[{k = #}, While[! CoprimeQ[#, f[k]], k++]; k] &, 79, 0] (* Michael De Vlieger, Nov 06 2022, after Jean-François Alcover at A276086 *)
  • PARI
    A356309(n) = (n+A356302(n)); \\ See code in the latter sequence.

Formula

a(n) = n + A356302(n).

A356316 Numbers k such that k divides the least j >= k for which k and A276086(j) are coprime, where A276086 is the primorial base exp-function.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 23, 24, 26, 28, 29, 30, 31, 32, 34, 35, 36, 37, 38, 41, 42, 43, 44, 46, 47, 48, 52, 53, 54, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 76, 77, 78, 79, 82, 83, 86, 88, 89, 90, 92, 94, 95, 96, 97, 101, 102, 103, 104, 105, 106, 107
Offset: 1

Views

Author

Antti Karttunen, Nov 04 2022

Keywords

Comments

Numbers k such that k divides A356309(k).

Crossrefs

Cf. A276086, A356309, A356315 (characteristic function), A356317 (complement).
Disjoint union of A324583 and A356318.

Programs

A358213 The index of the first occurrence of A002110(n) in A356309.

Original entry on oeis.org

1, 2, 3, 10, 35, 77, 286, 2431, 4199, 37145
Offset: 0

Views

Author

Antti Karttunen, Nov 05 2022

Keywords

Comments

A subsequence of A356314, and probably also of A356316 (from a(2)=3 onward of A356318 as well).
Also, from a(2)=3 onward conjectured to be the positions of records in A356302 (after its initial zero), while A358214 gives the conjectured record values.

Crossrefs

Programs

  • Mathematica
    f[nn_] := Block[{m = 1, i = 1, n = nn, p}, While[n > 0, p = Prime[i]; m *= p^Mod[n, p]; n = Quotient[n, p]; i++]; m]; q = P = 1; Reap[Do[k = j; While[! CoprimeQ[j, f[k]], k++]; If[k == P, Sow[j]; P *= Prime[q]; q++], {j, 0, 2500}] ][[-1, -1]] (* Michael De Vlieger, Nov 06 2022 *)
  • PARI
    \\ Very slow:
    A002110(n) = prod(i=1,n,prime(i));
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A356309(n) = { my(j=n); while(gcd(A276086(j),n)!=1,j++); (j); };
    A358213(n) = { my(x=A002110(n)); for(i=0,oo,if(A356309(i)==x,return(i))); };

Formula

A356309(a(n)) = a(n) + A358214(n).
a(n) = A002110(n) - A358214(n).
Showing 1-4 of 4 results.