The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A260815 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A260815

a(2) = 3; for n >= 3, a(n) = a(n-1) + gcd(n, a(n-1))^2.
(history; published version)

#30 by Charles R Greathouse IV at Thu Sep 08 08:46:13 EDT 2022

PROG

(MAGMAMagma) I:=[0, 3]; Remove([n le 2 select I[n] else Self(n-1)+Gcd(n, Self(n-1))^2: n in [1..52]], 1);

Discussion

Thu Sep 08

08:46

OEIS Server: https://oeis.org/edit/global/2944

#29 by Bruno Berselli at Wed Apr 14 05:24:10 EDT 2021

STATUS

proposed

approved

#28 by Robert Israel at Tue Apr 13 22:54:35 EDT 2021

STATUS

editing

proposed

#27 by Robert Israel at Tue Apr 13 22:54:13 EDT 2021

CROSSREFS

Cf. A167195, A343402.

STATUS

proposed

editing

#26 by Robert Israel at Tue Apr 13 21:29:03 EDT 2021

STATUS

editing

proposed

#25 by Robert Israel at Tue Apr 13 21:28:53 EDT 2021

KEYWORD

nonn,changed,look

#24 by Michael De Vlieger at Tue Apr 13 21:28:08 EDT 2021

MATHEMATICA

Nest[Append[#1, #1[[-1]] + GCD[#2, #1[[-1]]]^2] & @@ {#, Length[#] + 2} &, {3}, 50] (* Michael De Vlieger, Apr 13 2021 *)

STATUS

proposed

editing

#23 by Robert Israel at Tue Apr 13 21:22:04 EDT 2021

STATUS

editing

proposed

#22 by Robert Israel at Tue Apr 13 21:21:58 EDT 2021

LINKS

Robert Israel, <a href="/A260815/b260815.txt">Table of n, a(n) for n = 2..10000</a>

MAPLE

N:= 100: # for a(2)..a(N)

A:= Array(2..N):

A[2]:= 3:

for n from 3 to N do

A[n]:= A[n-1]+igcd(n, A[n-1])^2

od:

seq(A[i], i=2..N); # Robert Israel, Apr 13 2021

STATUS

approved

editing

#21 by N. J. A. Sloane at Sun Aug 02 17:39:16 EDT 2015

STATUS

editing

approved