OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..35000
FORMULA
MATHEMATICA
f[n_] := (Times @@ Power[If[# == 1, 1, NextPrime@ #] & /@ First@ #, Last@ #] + 1)/2 &@ Transpose@ FactorInteger@ n; g[n_] := Times @@ Power[If[# == 1, 1, NextPrime[#, -1]] & /@ First@ #, Last@ #] &@ Transpose@ FactorInteger[2 n - 1]; s = Select[Range@ 144, Xor[EvenQ@ f@ #, OddQ@ g@ #] &]; Table[Count[s, k_ /; k <= n], {n, 84}] (* Michael De Vlieger, Mar 17 2016 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Mar 17 2016
STATUS
approved