A284263 a(n) = A252459(2*A000040(n)), a(0) = 0 by convention.

0, 0, 0, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9

Offset: 0

Author

Antti Karttunen, Mar 24 2017

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 0..11000

Crossrefs

Cf. A000040, A002110, A251719, A252459, A284262.

Programs

Mathematica

a[n_] := If[n<1, 0, Block[{k=1}, While[Prime[n + k  - 1] > Prime[k]^2, k++]; k - 1]]; Table[a[n], {n, 0, 130}] (*  Indranil Ghosh, Mar 24 2017 *)

PARI

A284263(n) = { my(k=1); if(0==n, 0, while(prime(n+k-1) > (prime(k)^2), k = k+1);(k-1)); };

Python

from sympy import prime
def a(n):
    if n<1: return 0
    k=1
    while prime(n + k - 1)>prime(k)**2:k+=1
    return k - 1 # Indranil Ghosh, Mar 24 2017

Scheme

(define (A284263 n) (if (zero? n) n (A252459 (* 2 (A000040 n)))))

Formula

a(0) = 0, for n >= 1, a(n) = A252459(2*A000040(n)).

a(n) = A252459(A002110(n)).