The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A125249 Numbers n for which the absolute values of the abundances of n, n^2 and n^3 are all prime numbers. 0
 289, 201601, 222784, 638401, 868562, 910116, 4694048, 4950625, 8994001, 9054081, 19855936, 30085225, 32385152, 47623801, 55100929, 72182016, 78952178, 85099058, 86303522, 91910569, 104040000, 105678400, 111175936, 112530002, 128504896, 133702969, 193043236, 204404209, 216001809, 237961476 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE n=289; The abundance of 289 is -271, the abundance of 83521 (289^2) is -78301, the abundance of 24137569 (289^3) is -22628971 - all of which are negatives of primes. PROG (PARI) {for(n=1, 1000000, if(isprime(abs(sigma(n)-2*n))&&isprime(abs(sigma(n^2)-2*n^2))&&isprime(abs(sigma(n^3)-2*n^3)), print1(n, ", ")))} CROSSREFS Cf. A088005, A125236, A125237. Sequence in context: A226747 A260866 A252360 * A013761 A013883 A180701 Adjacent sequences: A125246 A125247 A125248 * A125250 A125251 A125252 KEYWORD nonn AUTHOR Jason G. Wurtzel, Nov 26 2006 EXTENSIONS More terms from Stefan Steinerberger, May 29 2007 a(21)-a(24) from Donovan Johnson, Feb 19 2009 a(25)-a(30) from Jason G. Wurtzel, Sep 24 2014 STATUS approved

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

Last modified November 27 00:20 EST 2022. Contains 358362 sequences. (Running on oeis4.)