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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064938 Nonprimes such that gcd(n, prime(n)^2 - 1) is n. 1
1, 4, 6, 8, 10, 12, 14, 20, 24, 42, 48, 60, 63, 70, 72, 80, 84, 108, 120, 124, 126, 153, 156, 182, 240, 246, 264, 286, 327, 372, 374, 440, 492, 516, 552, 1008, 1053, 1664, 1941, 2160, 2494, 3048, 3741, 4116, 4136, 4144, 4152, 5106, 5698, 6012, 6458, 6459 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

LINKS

Harry J. Smith, Table of n, a(n) for n=1,...,160

MATHEMATICA

Select[ Range[10^4], !PrimeQ[ # ] && GCD[ #, Prime[ # ]^2 - 1] == # & ]

PROG

(PARI) { default(primelimit, 4294965247); n=0; for (m=1, 10^9, if (isprime(m), next); if (gcd(m, prime(m)^2 - 1) == m, write("b064938.txt", n++, " ", m); if (n==160, return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 30 2009]

CROSSREFS

Cf. A064830.

Sequence in context: A186331 A061344 A066664 * A050990 A161546 A167179

Adjacent sequences:  A064935 A064936 A064937 * A064939 A064940 A064941

KEYWORD

easy,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 26 2001

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

Content is available under The OEIS End-User License Agreement .

Last modified February 16 12:15 EST 2012. Contains 205909 sequences.