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 1-2 of 2 results.

A348035 Multiply-perfect numbers k that have a unitary divisor d such that sigma(d)*d = k.

Original entry on oeis.org

1, 6, 28, 120, 496, 672, 8128, 523776, 33550336, 1379454720, 8589869056, 137438691328, 2305843008139952128, 203820700083634254643200, 2658455991569831744654692615953842176
Offset: 1

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Author

Antti Karttunen, Sep 26 2021

Keywords

Comments

At least the even terms of A000396 are all present, thus if there are an infinite number of Mersenne primes (A000668), then it implies that this sequence is infinite as well.

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Crossrefs

Subsequence of A348031. Intersection of A007691 and A348034.
Cf. A000396, A000668.

A348032 Multiply-perfect numbers k that do not have a divisor d such that sigma(d)*d = k.

Original entry on oeis.org

2178540, 45532800, 459818240, 1476304896, 14182439040, 31998395520, 43861478400, 51001180160, 518666803200, 704575228896, 13661860101120, 30823866178560, 181742883469056, 740344994887680, 796928461056000, 6088728021160320, 20158185857531904, 212517062615531520, 622286506811515392, 69357059049509038080, 87934476737668055040
Offset: 1

Views

Author

Antti Karttunen, Sep 26 2021

Keywords

Comments

Numbers k in A007691 for which A327153(k) = 0, that are not in A327165.
Question: Is A323653 a subsequence of this sequence? See also conjecture in A348033.

Links

Crossrefs

Cf. A348031 (complement in A007691).
Cf. A327153, A327165, A348033.

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Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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