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A217141
Numbers n such that phi(n) = phi(n+12) and are not divisible by 2.
5
143, 157, 203, 247, 273, 1147, 1209, 1679, 2147, 2279, 2375, 2445, 2705, 2747, 4331, 4687, 5049, 6107, 7367, 7835, 7869, 7979, 7991, 9167, 12127, 17145, 18501, 18753, 18981, 19803, 22987, 26733, 27359, 29097, 29987, 32829, 35485, 35763, 37653, 37851, 39907
OFFSET
1,1
LINKS
PROG
(PARI) {op=vector(N=12); Nd6=N/6; for( n=1, 1e4, if( op[n%N+1]+0==op[n%N+1]=eulerphi(n), if ((n-N) % Nd6 != 0, print1(n-N, ", "))))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Sep 27 2012
STATUS
approved