The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A308971 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A308971

Largest prime factor of A001008(n), numerator of n-th harmonic number; a(1) = 1.
(history; published version)

#18 by Alois P. Heinz at Mon Feb 24 08:07:51 EST 2020

STATUS

proposed

approved

#17 by Amiram Eldar at Mon Feb 24 08:07:15 EST 2020

STATUS

editing

proposed

#16 by Amiram Eldar at Mon Feb 24 07:48:27 EST 2020

FORMULA

a(n) = A006530(A001008(n)). - Amiram Eldar, Feb 24 2020

CROSSREFS

Cf. A001008, A006530.

#15 by Amiram Eldar at Mon Feb 24 07:46:43 EST 2020

LINKS

Amiram Eldar, <a href="/A308971/b308971.txt">Table of n, a(n) for n = 1..325</a>

STATUS

approved

editing

#14 by Bruno Berselli at Fri Jul 12 04:20:35 EDT 2019

STATUS

reviewed

approved

#13 by Michel Marcus at Fri Jul 12 04:11:05 EDT 2019

STATUS

proposed

reviewed

#12 by M. F. Hasler at Fri Jul 12 03:47:50 EDT 2019

STATUS

editing

proposed

#11 by M. F. Hasler at Fri Jul 12 03:47:36 EDT 2019

PROG

(PARI) rowa(n)={if(n>1, factor(A001008(n))[1, 1], 1)}

STATUS

proposed

editing

#10 by Michael De Vlieger at Thu Jul 04 22:27:21 EDT 2019

STATUS

editing

proposed

Discussion

Thu Jul 11

10:26

Felix Fröhlich: Maybe rename the PARI function to a(n)? It does not return a row, but a single factor. A function name like "row()" to me suggests a function that returns a vector of values. Perhaps that's just me, though.

Fri Jul 12

03:47

M. F. Hasler: Of course you are completely right!

#9 by Michael De Vlieger at Thu Jul 04 22:27:19 EDT 2019

MATHEMATICA

Array[FactorInteger[Numerator@HarmonicNumber[#]][[-1, 1]] &, 35] (* Michael De Vlieger, Jul 04 2019 *)

STATUS

proposed

editing