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A307587
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Numbers k such that the determinant of the Vandermonde matrix of their digits is equal to phi(k), the Euler totient function of k.
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2
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1, 2, 190, 280, 480, 1073, 1674, 1736, 4850, 15867, 16230, 16302, 23715, 24056, 25064, 35712, 52976, 54730, 75184, 105342, 456382, 964325
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OFFSET
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1,2
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COMMENTS
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Tested all the 8877691 numbers with distinct digits; no additional terms. - Giovanni Resta, Apr 16 2019
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LINKS
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EXAMPLE
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| 1 1 1 |
det | 1 9 81 | = 72 = phi(190).
| 1 0 0 |
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MAPLE
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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);
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CROSSREFS
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KEYWORD
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nonn,base,fini,full
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AUTHOR
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STATUS
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approved
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