The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A063506 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A063506

a(n) = phi(a(n-1)) * number of divisors of a(n-1), a(1)=3.
(history; published version)

#4 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009

KEYWORD

nonn,new

nonn

AUTHOR

Jason Earls (jcearlszevi_35711(AT)cableoneyahoo.netcom), Aug 09 2001

#3 by N. J. A. Sloane at Wed Sep 22 03:00:00 EDT 2004

KEYWORD

nonn,new

nonn

AUTHOR

Jason Earls (jcearls(AT)4grccableone.comnet), Aug 09 2001

#2 by N. J. A. Sloane at Sat Jun 12 03:00:00 EDT 2004

KEYWORD

nonn,new

nonn

AUTHOR

Jason Earls (jcearls(AT)kskc4grc.netcom), Aug 09 2001

#1 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

NAME

a(n) = phi(a(n-1) * number of divisors of a(n-1), a(1)=3.

DATA

3, 4, 6, 8, 16, 40, 128, 512, 2560, 20480, 212992, 2949120, 80216064, 3019898880, 130459631616, 7827577896960, 935134639423488, 128247036263792640, 22024291027701989376, 7222873082376801484800, 4118350906606118082969600

OFFSET

1,1

PROG

(PARI) s(n)=if(n<2, n+2, eulerphi(s(n-1))*numdiv(s(n-1)) ); for(n=1, 22, print(s(n)))

KEYWORD

nonn

AUTHOR

Jason Earls (jcearls(AT)kskc.net), Aug 09 2001

STATUS

approved