A245097 Number of primes greater than n and not greater than the smallest pseudoprime to base n.

2, 67, 22, 4, 27, 8, 5, 0, 5, 7, 1, 13, 2, 0, 62, 9, 7, 2, 6, 0, 8, 11, 2, 0, 0, 0, 9, 5, 1, 5, 4, 0, 12, 0, 4, 13, 2, 0, 12, 12, 14, 33, 7, 0, 7, 18, 3, 0, 3, 0, 3, 8, 2, 0, 2, 0, 2, 16, 6, 51, 6, 0, 50, 0, 11, 6, 4, 0, 4, 20, 7, 3, 8, 0, 3, 0, 32, 47, 2, 0

Offset: 1

Author

Reinhard Zumkeller, Nov 12 2014

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000720, A007535, A010051.

Programs

Haskell

a245097 n = sum $ map a010051' [n + 1 .. a007535 n]

PARI

f(n) = forcomposite(m=n+1, , if(Mod(n, m)^(m-1)==1, return(m))); \\ A007535
a(n) = primepi(f(n)) - primepi(n); \\ Michel Marcus, Jan 24 2022

Formula

a(n) = Sum {k=n+1..A007535(n)} A010051(k).

a(n) = A000720(A007535(n)) - A000720(n).