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.

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A346089 a(n) = n divided by the smallest divisor d of n for which A002034(d) = A002034(n), where A002034(n) is the smallest positive integer k such that k! is a multiple of n.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 3, 1, 1, 2, 1, 4, 3, 2, 1, 6, 1, 2, 1, 4, 1, 6, 1, 1, 3, 2, 5, 4, 1, 2, 3, 8, 1, 6, 1, 4, 5, 2, 1, 3, 1, 2, 3, 4, 1, 2, 5, 8, 3, 2, 1, 12, 1, 2, 9, 2, 5, 6, 1, 4, 3, 10, 1, 8, 1, 2, 3, 4, 7, 6, 1, 5, 3, 2, 1, 12, 5, 2, 3, 8, 1, 10, 7, 4, 3, 2, 5, 3, 1, 2, 9, 4, 1, 6, 1, 8, 15
Offset: 1

Views

Author

Antti Karttunen, Jul 05 2021

Keywords

Crossrefs

Cf. A002034, A345935, A345936, A345944 (positions of 1's), A346088.
Cf. also A344759.
Differs from A302776 for the first time at n=27, where a(27) = 1, while A302776(27) = 3.

Programs

  • PARI
    A002034(n) = if(1==n,n,my(s=factor(n)[, 1], k=s[#s], f=Mod(k!, n)); while(f, f*=k++); (k)); \\ After code in A002034.
    A346089(n) = { my(x=A002034(n)); fordiv(n,d,if(A002034(d)==x, return(n/d))); };

Formula

a(n) = n / A346088(n).

A354998 Smallest divisor d of n for which A344005(d) = A344005(n), where A344005(n) is the smallest positive integer m such that n divides m*(m+1).

Original entry on oeis.org

1, 1, 3, 4, 5, 3, 7, 8, 9, 5, 11, 4, 13, 7, 15, 16, 17, 9, 19, 5, 7, 11, 23, 24, 25, 13, 27, 28, 29, 15, 31, 32, 33, 17, 35, 9, 37, 19, 13, 40, 41, 7, 43, 44, 45, 23, 47, 16, 49, 25, 51, 13, 53, 27, 11, 8, 19, 29, 59, 60, 61, 31, 63, 64, 65, 33, 67, 17, 69, 35, 71, 9, 73, 37, 25, 76, 77, 13, 79, 16, 81, 41, 83, 84
Offset: 1

Views

Author

Antti Karttunen, Jun 17 2022

Keywords

Crossrefs

Programs

  • Mathematica
    s[n_] := Module[{m = 1}, While[! Divisible[m*(m + 1), n], m++]; m]; a[n_] := Module[{sn = s[n], ds = Divisors[n]}, Do[If[s[d] == sn, Return[d]], {d, ds}]]; Array[a, 100] (* Amiram Eldar, Jun 17 2022 *)
  • PARI
    A344005(n) = for(m=1, oo, if((m*(m+1))%n==0, return(m))); \\ From A344005
    A354998(n) = { my(x=A344005(n)); fordiv(n, d, if(A344005(d)==x, return(d))); };

Formula

a(n) = n / A354999(n).
Showing 1-2 of 2 results.