login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A082021 a(0) = 7; for n > 0, a(n) is the greatest prime factor of PP(PP(a(n-1)))*a(n-1)+2 where PP(n) is an abbreviation for PreviousPrime(n). 2
7, 23, 131, 47, 643, 2459, 2000807, 503347241, 82125909539251, 9617692012399, 55555555342491359799151, 1116817987709786226917069, 578610396154837, 66992050984853, 254497141, 1660738053545999, 201525986561, 25600818891233, 796725607788661087 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..18.

MATHEMATICA

NestWhileList[FactorInteger[2+#*Prime[PrimePi[ # ]-2]][[ -1, 1]] &, 7, True, 8] - T. D. Noe, Nov 15 2006

NestList[FactorInteger[NextPrime[NextPrime[#, -1], -1]#+2][[-1, 1]]&, 7, 20] (* Harvey P. Dale, Dec 26 2017 *)

CROSSREFS

Cf. A082032, A031441, A031442.

Sequence in context: A064640 A064639 A064638 * A227254 A080082 A158954

Adjacent sequences:  A082018 A082019 A082020 * A082022 A082023 A082024

KEYWORD

nonn

AUTHOR

Yasutoshi Kohmoto, May 10 2003

EXTENSIONS

Description corrected by Rick L. Shepherd, Dec 19 2004

Corrected by T. D. Noe, Nov 15 2006

More terms from Harvey P. Dale, Dec 26 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 21 08:27 EDT 2018. Contains 316405 sequences. (Running on oeis4.)