The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A217662 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A217662

For n > 2 , a(n) = a(n-2) + lcm(a(n-2), n-1) with a(1)=2, a(2)=2.
(history; published version)

#15 by Harvey P. Dale at Thu Aug 20 18:48:55 EDT 2020

STATUS

editing

approved

#14 by Harvey P. Dale at Thu Aug 20 18:48:52 EDT 2020

MATHEMATICA

nxt[{n_, a_, b_}]:={n+1, b, a+LCM[a, n]}; NestList[nxt, {2, 2, 2}, 40][[All, 2]] (* Harvey P. Dale, Aug 20 2020 *)

STATUS

approved

editing

#13 by Susanna Cuyler at Sun Mar 04 17:47:33 EST 2018

STATUS

proposed

approved

#12 by Jon E. Schoenfield at Sun Mar 04 16:06:34 EST 2018

STATUS

editing

proposed

#11 by Jon E. Schoenfield at Sun Mar 04 16:06:32 EST 2018

NAME

For n > 2 , a(n) = a(n-2) + LCMlcm(a(n-2), n-1) with a(1)=2, a(2)=2.

COMMENTS

A217663(n) = a(n+2)/a(n)-1 consists of 1's and primes only.

FORMULA

For prime p > 2, a(p+1) = (p+1)*a(p-1), which proves the statement in A217663. - M. F. Hasler, Oct 11 2012

STATUS

approved

editing

#10 by M. F. Hasler at Thu Oct 11 08:58:05 EDT 2012

STATUS

editing

approved

#9 by M. F. Hasler at Thu Oct 11 08:58:00 EDT 2012

COMMENTS

A217663(n)=a(n+2)/a(n)-1 consists of 1's and primes only.

FORMULA

For prime p>2, a(p+1)=(p+1)*a(p-1), which proves the statement in A217663. - M. F. Hasler, Oct 11 2012

STATUS

approved

editing

#8 by T. D. Noe at Wed Oct 10 13:44:13 EDT 2012

STATUS

editing

approved

#7 by T. D. Noe at Wed Oct 10 13:43:54 EDT 2012

NAME

For n > 2 , a(n) = a(n-2) +lcm LCM(a(n-2), n-1) with a(1)=2, a(2)=2.

DATA

2, 2, 4, 8, 8, 48, 32, 384, 64, 1536, 384, 18432, 768, 258048, 6144, 1548288, 12288, 27869184, 49152, 557383680, 294912, 1114767360, 3538944, 26754416640, 7077888, 160526499840, 99090432, 321052999680, 198180864, 9631589990400, 1189085184, 308210879692800

MATHEMATICA

t = {2, 2}; Do[AppendTo[t, t[[-2]] + LCM[n-1, t[[-2]]]], {n, 3, 40}]; t (* T. D. Noe, Oct 10 2012 *)

STATUS

proposed

editing

#6 by Pedja Terzic at Wed Oct 10 13:24:35 EDT 2012

STATUS

editing

proposed