OFFSET
1,2
REFERENCES
K. Miller, Solutions of phi(n) = phi(n+1) for 1 <= n <= 500000. Unpublished, 1972. [Cf. Math. Comp., Vol. 27, p. 447, 1973.]
D. Shanks, Solved and Unsolved Problems in Number Theory, 2nd. ed., Chelsea, 1978, p. 225.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
P. J. Cameron and D. A. Preece, Notes on primitive lambda-roots.
K. Miller, The equation phi(n) = phi(n+1), Unpublished M.S., ND.
K. Miller, Solutions of phi(n) = phi(n+1) for 1 <= n <= 500000, Mathematics of Computation 27 (1973), 47-48. (Annotated scanned copy)
PROG
(PARI) {my(z=znstar(1)); for(n=1, 10^10, my(z1=znstar(n+1)); if(z[1]==z1[1]&&z[2]==z1[2], print1(n, ", ")); z=z1; ); } \\ Joerg Arndt, Mar 17 2016
(PARI) list(lim)=my(v=List(), old=[1, []]); forfactored(n=2, lim\1+1, my(cur=znstar(n)[1..2]); if(old==cur, listput(v, n[1]-1)); old=cur); Vec(v) \\ Charles R Greathouse IV, Jul 17 2022
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
EXTENSIONS
More terms from David W. Wilson
STATUS
approved