1,6

a(n) = number of 4k+1 primes (A002144) among primes in range 2 .. A000040(n).

Antti Karttunen, Table of n, a(n) for n = 1..65537

Other identities. For all n >= 1:

a(A080147(n)) = n.

a(n) + A267098(n) = n-1.

(Scheme, with Antti Karttunen's IntSeq-library)

(define A267097 (LEFTINV-LEASTMONO 1 1 A080147))

Cf. A000040, A002144, A080147, A267098.

Cf. also A267101.

Sequence in context: A120565 A244989 A296021 * A194198 A189674 A156250

Adjacent sequences: A267094 A267095 A267096 * A267098 A267099 A267100

nonn

Antti Karttunen, Feb 01 2016

approved