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n + 1 - d(n) - phi(n) never takes these values (conjecture).
0

%I #18 Oct 06 2020 03:32:31

%S 2,13,67,93,123,133,141,173,187,193,205,217,229,245,253,257,283,285,

%T 293,303,317,319,325,333,341,389,393,397,405,415,427,445,453,467,473,

%U 483,491,493,509,525,527,533,537,549,557,571,573,581,587,589

%N n + 1 - d(n) - phi(n) never takes these values (conjecture).

%D R. K. Guy, Unsolved Problems in Number Theory, Springer, 3rd ed. (2004), 101.

%Y Cf. A045763.

%K nonn

%O 1,1

%A _Wouter Meeussen_

%E Added "conjecture" to title. - _Wouter Meeussen_, Oct 05 2020