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.

A338224 Multiplicative with a(A246655(k)) = prime(k) for any k > 0 (where prime(k) denotes the k-th prime number).

Original entry on oeis.org

1, 2, 3, 5, 7, 6, 11, 13, 17, 14, 19, 15, 23, 22, 21, 29, 31, 34, 37, 35, 33, 38, 41, 39, 43, 46, 47, 55, 53, 42, 59, 61, 57, 62, 77, 85, 67, 74, 69, 91, 71, 66, 73, 95, 119, 82, 79, 87, 83, 86, 93, 115, 89, 94, 133, 143, 111, 106, 97, 105, 101, 118, 187, 103
Offset: 1

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Author

Rémy Sigrist, Jan 30 2021

Keywords

Comments

All terms are distinct and squarefree.
This sequence has similarities with A160102, however some squarefree numbers do not appear here.

Examples

			a(3) = a(A246655(2)) = prime(2) = 3.
a(4) = a(A246655(3)) = prime(3) = 5.
a(12) = a(3) * a(4) = 3*5 = 15.
		

Crossrefs

Programs

  • PARI
    pk = select(v -> omega(v)==1, [1..m=64]); for (n=1, m, f=factor(n); print1 (prod(k=1, #f~, prime(setsearch(pk, f[k,1]^f[k,2])))", "))
    
  • Python
    from math import prod
    from sympy import prime, primepi, integer_nthroot, factorint
    def A338224(n): return prod(prime(sum(primepi(integer_nthroot(p**e,k)[0]) for k in range(1,(p**e).bit_length()))) for p, e in factorint(n).items()) # Chai Wah Wu, Jan 19 2025