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.

A278246 a(n) = least number with the same prime signature as n*(n+3)/2.

Original entry on oeis.org

2, 2, 4, 6, 12, 8, 6, 12, 24, 6, 6, 60, 24, 6, 24, 24, 30, 24, 6, 30, 180, 12, 6, 144, 60, 6, 48, 30, 48, 60, 6, 240, 120, 6, 30, 120, 60, 6, 60, 60, 30, 120, 6, 30, 1080, 12, 12, 360, 60, 12, 48, 210, 60, 48, 30, 60, 420, 6, 6, 840, 96, 30, 120, 96, 210, 60, 30, 30, 360, 30, 6, 1800, 30, 30, 180, 30, 840, 96, 6, 120, 480, 30, 6, 420, 420, 6, 120, 420, 30, 120
Offset: 1

Views

Author

Antti Karttunen, Nov 21 2016

Keywords

Comments

For n > 2, 6 <= a(n) <= n*(n+3)/2. The upper bound occurs for n = 1, 45, 165, 525, 672, 1152, and no others up to 10^9. (Probably this occurs only finitely many times.) - Charles R Greathouse IV, Nov 23 2016

Links

Crossrefs

Cf. A000096, A046523, A278247, A278251, A278253, A278255.

Programs

Formula

a(n) = A046523(A000096(n)).

A278251 Least number with the prime signature of the n-th central polygonal number.

Original entry on oeis.org

1, 1, 2, 2, 2, 6, 2, 2, 6, 2, 6, 6, 6, 2, 6, 2, 2, 30, 2, 8, 6, 2, 2, 12, 6, 2, 30, 6, 2, 6, 6, 12, 6, 6, 2, 6, 6, 6, 30, 2, 6, 6, 2, 6, 6, 6, 6, 30, 6, 6, 30, 2, 6, 6, 6, 2, 30, 6, 2, 30, 2, 6, 30, 2, 6, 30, 6, 2, 60, 12, 2, 6, 2, 6, 6, 30, 2, 6, 2, 2, 60, 2, 30, 6, 6, 6, 6, 6, 30, 30, 2, 2, 6, 6, 6, 30, 6, 6, 6, 6, 2, 210, 2, 30, 6, 6, 2, 30, 30, 6, 30, 2, 2
Offset: 0

Views

Author

Antti Karttunen, Nov 21 2016

Keywords

Comments

Almost all terms seem to be primorials, 4871 of the first 5212, in other words, most terms of A002061 (in the same range) are squarefree.

Links

Crossrefs

Cf. A002061, A046523.
Cf. also A278246, A278247, A278253.

Programs

Formula

a(n) = A046523(A002061(n)).

A278255 Least number with the prime signature of the n-th pentagonal number.

Original entry on oeis.org

1, 2, 12, 6, 6, 6, 30, 12, 12, 6, 48, 210, 6, 6, 210, 24, 12, 12, 60, 30, 30, 30, 30, 60, 12, 30, 1080, 30, 6, 30, 30, 240, 60, 6, 420, 60, 30, 6, 210, 420, 6, 120, 192, 30, 60, 6, 210, 840, 12, 12, 420, 210, 6, 120, 210, 60, 210, 6, 120, 210, 30, 30, 420, 96, 30, 30, 180, 210, 30, 210, 30, 1260, 6, 30, 5040, 30, 210, 30, 30, 120, 144, 60, 60, 210, 30, 6, 2310
Offset: 1

Views

Author

Antti Karttunen, Nov 21 2016

Keywords

Links

Crossrefs

Cf. A000326, A046523.
Cf. also A278246, A278247, A278251, A278253, A278254.

Programs

Formula

a(n) = A046523(A000326(n)).
Showing 1-3 of 3 results.

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