login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064938 Nonprimes k such that k divides prime(k)^2 - 1. 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; text; 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)) ) } \\ Harry J. Smith, Sep 30 2009

CROSSREFS

Cf. A064830.

Sequence in context: A242396 A061344 A066664 * A050990 A289425 A225514

Adjacent sequences:  A064935 A064936 A064937 * A064939 A064940 A064941

KEYWORD

easy,nonn

AUTHOR

Robert G. Wilson v, Oct 26 2001

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 17 05:30 EDT 2021. Contains 345080 sequences. (Running on oeis4.)