A063798 phi(s(n^3)) is a square, where s(n) is sigma(n)-n (A001065).

4, 7, 9, 61, 73, 81, 121, 144, 431, 727, 919, 1596, 2413, 2593, 2809, 3966, 6561, 6827, 9551, 10593, 12791, 17053, 29959, 31238, 33791, 45115, 47051, 76157, 79898, 85607, 140891, 148151, 192887, 203843, 212461, 311293, 381739, 397259

Offset

1,1

Links

Table of n, a(n) for n=1..38.

Prog

(PARI) s(n) = sigma(n)-n; for(n=2, 10^6, if(issquare(eulerphi(s(n^3))), print(n)))

Crossrefs

Cf. A001065.

Sequence in context: A346554 A022541 A330695 * A084035 A103702 A118517

Adjacent sequences: A063795 A063796 A063797 * A063799 A063800 A063801

Keyword

nonn

Author

Jason Earls, Aug 19 2001

Extensions

More terms from Dean Hickerson, Aug 22 2001

Status

approved