The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A241917

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A241917

If n is a prime with index i, p_i, a(n) = i, (with a(1)=0), otherwise difference (i-j) of the indices of the two largest primes p_i, p_j, i >= j in the prime factorization of n: a(n) = A061395(n) - A061395(A052126(n)).
(history; published version)

#31 by Michael De Vlieger at Wed Jul 10 09:36:35 EDT 2024

STATUS

proposed

#30 by Antti Karttunen at Wed Jul 10 07:08:39 EDT 2024

STATUS

editing

#29 by Antti Karttunen at Wed Jul 10 07:06:32 EDT 2024

COMMENTS

a(A000040(k)) = k.

#28 by Antti Karttunen at Wed Jul 10 07:05:38 EDT 2024

CROSSREFS

Cf. A241919, A242411 for other variants.

#27 by Antti Karttunen at Wed Jul 10 07:03:25 EDT 2024

COMMENTS

Note: the two largest primes in the multiset of prime divisors of n are equal for all numbers that are in A070003, thus, after a(1)=0, A070003 gives the positions of the other zeros in this sequence. Cf. A241919, A242411 for other variants.

CROSSREFS

Cf. A241919, A242411, A052126, A061395, A070003, A122111, A241909.

#26 by Antti Karttunen at Wed Jul 10 07:01:57 EDT 2024

LINKS

PROG

STATUS

approved

#25 by N. J. A. Sloane at Sat May 20 10:22:23 EDT 2017

STATUS

reviewed

#24 by Michel Marcus at Sat May 20 00:30:14 EDT 2017

STATUS

proposed

#23 by Indranil Ghosh at Fri May 19 12:10:17 EDT 2017

STATUS

editing

#22 by Indranil Ghosh at Fri May 19 12:10:12 EDT 2017

PROG

from sympy import factorint, primefactors, primepi

STATUS

proposed