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A334196
a(1) = 0, then after the first differences of A003434.
2
0, 1, 1, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, -1, 1, 0, 1, -2, 1, 0, 0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 1, 0, 0, 0, 0, -1, 1, -1, 1, 0, 1, -2, 1, 0, 0, 0, 1, -1, 0, 0, 1, -1, 1, -2, 2, -1, 0, 0, 1, -1, 1, -1, 0, 1, 0, -1, 1, 0, 0, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 0, -1, 1, 1, -2, 2, -2, 1, 0, 1, -2, 1, 0, 0, 0, 0, 0, 1, -2, 1, 0, 1, -1, 1, -1, 0
OFFSET
1,18
COMMENTS
Also, from a(2) onward the first differences of A049108, and from a(3) onward the first differences of A032358.
LINKS
FORMULA
a(1) = 0; and for n > 1, a(n) = A003434(n) - A003434(n-1).
MATHEMATICA
Differences[Array[Length[FixedPointList[EulerPhi, #]] &, 100, 0]] (* Paolo Xausa, Aug 18 2024 *)
PROG
(PARI)
A003434(n) = for(k=0, n, n>1 || return(k); n=eulerphi(n));
A334196(n) = if(1==n, 0, A003434(n)-A003434(n-1));
CROSSREFS
KEYWORD
sign
AUTHOR
Antti Karttunen, Apr 18 2020
STATUS
approved