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 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. 2
 1, 2, 190, 280, 480, 1073, 1674, 1736, 4850, 15867, 16230, 16302, 23715, 24056, 25064, 35712, 52976, 54730, 75184, 105342, 456382, 964325 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Tested all the 8877691 numbers with distinct digits; no additional terms. - Giovanni Resta, Apr 16 2019 LINKS Table of n, a(n) for n=1..22. EXAMPLE | 1 1 1 | det | 1 9 81 | = 72 = phi(190). | 1 0 0 | 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); CROSSREFS Cf. A000005, A307586. Sequence in context: A252765 A172801 A318195 * A235680 A085937 A142890 Adjacent sequences: A307584 A307585 A307586 * A307588 A307589 A307590 KEYWORD nonn,base,fini,full AUTHOR Paolo P. Lava, Apr 16 2019 STATUS approved

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Last modified August 10 12:00 EDT 2024. Contains 375056 sequences. (Running on oeis4.)