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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A081303 gpf(m) - 2*spf(m), where gpf(m) is the greatest and spf(m) is the smallest prime factor of m (A006530, A020639).

Original entry on oeis.org

-1, -2, -3, -2, -5, -1, -7, -2, -3, 1, -11, -1, -13, 3, -1, -2, -17, -1, -19, 1, 1, 7, -23, -1, -5, 9, -3, 3, -29, 1, -31, -2, 5, 13, -3, -1, -37, 15, 7, 1, -41, 3, -43, 7, -1, 19, -47, -1, -7, 1, 11, 9, -53, -1, 1, 3, 13, 25, -59, 1, -61, 27, 1, -2, 3, 7, -67, 13, 17, 3, -71, -1, -73, 33, -1, 15
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 17 2003

Keywords

Crossrefs

Cf. A046665, A081304, A081305, A081306, A069900.

A081304 Number of numbers m <= n with prime factors less than 2*spf(m), where spf(m) is the smallest prime factor of m (A020639).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 9, 10, 11, 12, 12, 13, 14, 15, 16, 17, 17, 17, 17, 18, 19, 20, 20, 21, 21, 22, 22, 23, 24, 24, 24, 25, 26, 27, 27, 27, 27, 28, 28, 29, 29, 30, 30, 31, 32, 33, 33, 33, 33, 34, 35, 35, 35, 35, 35, 36, 36, 37, 37, 37, 38, 38, 38, 39, 39, 39, 39, 40, 41, 42
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 17 2003

Keywords

Comments

a(n)+A081305(n)=n; a(114)=A081305(114)=57;
a(n)>=n/2 for n<=114, a(n)114.

Crossrefs

Cf. A081306, A081303.
Showing 1-2 of 2 results.

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