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A291164
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Numbers k such that 2^psi(k) == -1 (mod k) where psi(k) = A001615(k).
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0
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1, 5, 25, 125, 625, 3125, 4097, 7361, 15625, 69649, 78125, 85073, 125137, 390625, 658529, 987377, 1184033, 1953125, 2127329, 2358529, 3187313, 3999137, 9765625, 11194993, 16777217, 16785409, 20128561, 20502593, 30030769, 36164593, 40094993, 48828125, 50281793
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OFFSET
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1,2
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LINKS
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EXAMPLE
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7361 is a term because 7361 = 17*433 divides 2^psi(7361) + 1 = 2^(18*434) + 1.
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PROG
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(PARI) a001615(n) = n*sumdivmult(n, d, issquarefree(d)/d);
is(n) = Mod(2, n)^a001615(n)==-1;
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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