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.

A370120 a(n) = A276085(A370117(n)), where A370117(n) is the denominator of n/A276086(A003415(n)), A003415 is the arithmetic derivative, A276086 is the primorial base exp-function, and A276085 is its inverse, the primorial base log-function.

Original entry on oeis.org

0, 0, 0, 1, 4, 1, 2, 1, 12, 6, 0, 1, 14, 1, 8, 0, 32, 1, 18, 1, 18, 8, 12, 1, 42, 4, 14, 25, 2, 1, 30, 1, 80, 12, 18, 6, 60, 1, 20, 14, 62, 1, 8, 1, 48, 31, 24, 1, 110, 14, 32, 18, 56, 1, 78, 10, 62, 20, 30, 1, 90, 1, 32, 19, 192, 12, 60, 1, 72, 24, 22, 1, 156, 1, 38, 43, 80, 18, 68, 1, 170, 108, 42, 1, 92, 16, 44
Offset: 0

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Author

Antti Karttunen, Feb 11 2024

Keywords

Crossrefs

Cf. A003415, A276085, A276086, A327859, A369964, A370115 (positions of 0's), A370117.

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1)); };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A370120(n) = { my(u=A276086(A003415(n))); A276085(u/gcd(n, u)); };

Formula

a(n) = A276085(A370117(n)).

A369964 a(n) = gcd(n, A276086(A003415(n))), where A003415 is the arithmetic derivative, and A276086 is the primorial base exp-function.

Original entry on oeis.org

1, 1, 2, 1, 1, 1, 6, 1, 1, 1, 10, 1, 3, 1, 2, 15, 1, 1, 6, 1, 5, 3, 2, 1, 3, 5, 2, 3, 7, 1, 2, 1, 1, 3, 2, 5, 1, 1, 2, 3, 5, 1, 42, 1, 1, 15, 2, 1, 3, 1, 50, 3, 1, 1, 6, 5, 7, 3, 2, 1, 3, 1, 2, 21, 1, 5, 2, 1, 1, 3, 70, 1, 1, 1, 2, 25, 1, 1, 6, 1, 5, 1, 2, 1, 21, 5, 2, 3, 1, 1, 6, 1, 1, 3, 2, 5, 3, 1, 98, 3, 25
Offset: 0

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Author

Antti Karttunen, Feb 11 2024

Keywords

Crossrefs

Cf. A003415, A276086, A327859, A370114 (fixed points, see also A369650), A370116, A370117.

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A369964(n) = gcd(n, A276086(A003415(n)));

Formula

a(n) = gcd(n, A327859(n)) = gcd(n, A276086(A003415(n))).
For n >= 1, a(n) = n / A370116(n).
For n >= 0, a(n) = A327859(n) / A370117(n).

A370115 Numbers k for which k is a multiple of A276086(A003415(k)), where A003415 is the arithmetic derivative, and A276086 is the primorial base exp-function.

Original entry on oeis.org

0, 1, 2, 10, 15, 161, 2189, 5005, 27030, 29861, 510221, 223092341
Offset: 1

Views

Author

Antti Karttunen, Feb 11 2024

Keywords

Comments

Question: Is the squarefreeness a necessary condition for the nonzero terms of this sequence?
Many of the terms occur also in A368703, because the arithmetic derivative of those terms is one of the primorial numbers, A002110.
If it exists, a(13) > 1241513984.

Crossrefs

Positions of 1's in A370117, positions of 0's in A370120.
Intersection of A048103 and A369650 is a subsequence of this sequence. See the comments in latter.
Cf. also A369970, A370114.

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    isA370115(n) = !(n%A276086(A003415(n)));

A370116 Numerator of n/A276086(A003415(n)), where A003415 is the arithmetic derivative, and A276086 is the primorial base exp-function.

Original entry on oeis.org

0, 1, 1, 3, 4, 5, 1, 7, 8, 9, 1, 11, 4, 13, 7, 1, 16, 17, 3, 19, 4, 7, 11, 23, 8, 5, 13, 9, 4, 29, 15, 31, 32, 11, 17, 7, 36, 37, 19, 13, 8, 41, 1, 43, 44, 3, 23, 47, 16, 49, 1, 17, 52, 53, 9, 11, 8, 19, 29, 59, 20, 61, 31, 3, 64, 13, 33, 67, 68, 23, 1, 71, 72, 73, 37, 3, 76, 77, 13, 79, 16, 81, 41, 83, 4, 17, 43
Offset: 0

Views

Author

Antti Karttunen, Feb 11 2024

Keywords

Crossrefs

Cf. A003415, A276086, A327859, A369964, A370114 (positions of 1's), A370117 (denominators).

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A370116(n) = (n/gcd(n, A276086(A003415(n))));

Formula

a(n) = n / A369964(n) = n / gcd(n, A276086(A003415(n))).
Showing 1-4 of 4 results.