A125249 Numbers n for which the absolute values of the abundances of n, n^2 and n^3 are all prime numbers.

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

Offset

1,1

Links

Table of n, a(n) for n=1..30.

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