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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A281686 Numbers k such that A001222(k) = A001222(A003415(k)).

Original entry on oeis.org

4, 8, 9, 14, 21, 25, 26, 27, 32, 33, 36, 38, 46, 48, 49, 50, 54, 57, 62, 69, 74, 80, 85, 88, 93, 94, 99, 100, 106, 121, 125, 128, 129, 133, 134, 145, 156, 166, 169, 176, 177, 178, 205, 207, 213, 216, 217, 218, 226, 230, 237, 240, 242, 243, 248, 249, 252, 253
Offset: 1

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Author

Colin Barker, Jan 27 2017

Keywords

Comments

Numbers k such that the number of prime divisors (counted with multiplicity) of k is equal to the number of prime divisors (counted with multiplicity) of the arithmetic derivative of k.

Links

Crossrefs

Cf. A001222, A003415, A209870, A281685.

Programs

  • PARI
    arde(n) = sum(i=1, #f=factor(n)~, n/f[1, i]*f[2, i])
select(k->bigomega(k)==bigomega(arde(k)), vector(400, k, k+1))
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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