A307587 Numbers k such that the determinant of the Vandermonde matrix of their digits is equal to phi(k), the Euler totient function of k.

1, 2, 190, 280, 480, 1073, 1674, 1736, 4850, 15867, 16230, 16302, 23715, 24056, 25064, 35712, 52976, 54730, 75184, 105342, 456382, 964325

Offset: 1

Author

Paolo P. Lava, Apr 16 2019

Keywords

• nonn
• base
• fini
• full

Comments

Tested all the 8877691 numbers with distinct digits; no additional terms. - Giovanni Resta, Apr 16 2019

Examples

			     | 1  1   1  |
det  | 1  9   81 | = 72  = phi(190).
     | 1  0   0  |
		

Crossrefs

Cf. A000005, A307586.

Programs

Maple

with(numtheory): with(linalg): P:=proc(q) local a,c,k,n;
for n from 1 to q do a:=convert(n,base,10): c:=[]:
for k from 1 to nops(a) do c:=[op(c), a[-k]]; od;
if phi(n)=det(vandermonde(c)) then print(n); fi; od; end: P(10^9);