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Search: id:A001837
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| A001837 |
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phi(2n+1) < phi(2n).
(Formerly M5406 N2349)
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+0
3
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| 157, 262, 367, 412, 472, 487, 577, 682, 787, 877, 892, 907, 997, 1072, 1207, 1237, 1312, 1402, 1522, 1567, 1627, 1657, 1732, 1852, 1942, 2047, 2062, 2152, 2194, 2257, 2362, 2437, 2467, 2557, 2572, 2677, 2722, 2782
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Greg Martin (gerg(AT)math.toronto.edu) writes: I recently calculated the smallest solution of phi(30n+1) < phi(30n) (Amer. Math. Monthly 106 (1999), no. 5, 449-451); it has 1116 digits.
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REFERENCES
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V. L. Klee, Jr., Some remarks on Euler's totient function, Amer. Math. Monthly, 54 (1947), 332.
J. O. Shallit, personal communication.
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MAPLE
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with(numtheory, phi); f := proc(n) if phi(2*n+1) < phi(2*n) then RETURN(n) fi end;
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MATHEMATICA
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Select[ Range[4000], EulerPhi[2# + 1] < EulerPhi[2# ] & ]
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CROSSREFS
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Cf. A000010.
Sequence in context: A142231 A020356 A142367 this_sequence A142581 A140625 A142874
Adjacent sequences: A001834 A001835 A001836 this_sequence A001838 A001839 A001840
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KEYWORD
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nonn
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AUTHOR
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njas
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