OFFSET
1,3
COMMENTS
a(n) is also the value on the axis "y" of the n-th inflection point in the structure of A211000.
LINKS
Paolo Xausa, Table of n, a(n) for n = 1..10000
MATHEMATICA
A211023[upto_]:=Module[{ep={0, 0}, angle=3/4Pi, turn=Pi/2}, Table[If[!PrimeQ[n], If[n>5&&PrimeQ[n-1], turn*=-1]; angle-=turn]; ep=AngleVector[ep, {Sqrt[2], angle}]; If[PrimeQ[n+1], Last[ep], Nothing], {n, 0, upto-1}]];
A211023[500] (* Paolo Xausa, Jan 14 2023 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Omar E. Pol, Mar 31 2012
STATUS
approved