A056743 a(n) = phi(2^prime(n) - 1)/prime(n); a(0) = 0 by convention.

0, 1, 2, 6, 18, 176, 630, 7710, 27594, 356960, 18407808, 69273666, 3697909056, 53630700752, 204064589160, 2992477516800, 169917983040000, 9770466930024800, 37800705069076950, 2202596295934991760

Offset: 0

Author

Robert G. Wilson v, Aug 14 2000

Keywords

• nonn

Crossrefs

Cf. A000020, A064535.

Programs

Maple

with numtheory; A056743 := proc(n) phi( 2^ithprime(n) - 1 )/ithprime(n); end;

Mathematica

Phi( A001348) / A000040. Table[EulerPhi[(2^Prime[n] - 1)]/Prime[n], {n, 1, 25}]