OFFSET
1,1
COMMENTS
Similar to prime binary digit sequence A010051.
In decimal notation A164292=0.1646823906345389353962381...
Characteristic function of A001097. - Georg Fischer, Aug 04 2021
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Index entries for characteristic functions [From Reinhard Zumkeller, Mar 29 2010]
FORMULA
a(n) = c(n) * ceiling(( c(n+2) + c(n-2) )/2), where c is the prime characteristic. - Wesley Ivan Hurt, Jan 31 2014
MATHEMATICA
Table[(PrimePi[n] - PrimePi[n - 1]) * Ceiling[(PrimePi[n + 2] - PrimePi[n + 1] + PrimePi[n - 2] - PrimePi[n - 3])/2], {n, 100}] (* Wesley Ivan Hurt, Jan 31 2014 *)
Table[If[PrimeQ[n]&&AnyTrue[n+{2, -2}, PrimeQ], 1, 0], {n, 120}] (* Harvey P. Dale, Jan 04 2025 *)
PROG
(Haskell)
a164292 1 = 0
a164292 2 = 0
a164292 n = signum (a010051' n * (a010051' (n - 2) + a010051' (n + 2)))
-- Reinhard Zumkeller, Feb 03 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Carlos Alves, Aug 12 2009
STATUS
approved