A113496 a(n) = smallest composite integer > c(n) and coprime to c(n), where c(n) is the n-th composite integer.

9, 25, 9, 10, 21, 25, 15, 16, 21, 25, 21, 22, 25, 25, 26, 27, 28, 33, 49, 33, 34, 35, 36, 49, 39, 40, 49, 55, 45, 46, 49, 49, 50, 51, 52, 55, 55, 56, 57, 58, 63, 77, 63, 64, 65, 66, 85, 69, 70, 81, 77, 75, 76, 77, 78, 85, 81, 82, 85, 85, 86, 87, 88, 91, 91, 92, 93, 94, 95, 96

Offset

1,1

Links

Table of n, a(n) for n=1..70.

Formula

a(n) = A113484(A002808(n)). - Robert G. Wilson v, Jan 12 2006

Mathematica

Composite[n_Integer] := FixedPoint[n + PrimePi[ # ] + 1 &, n + PrimePi[n] + 1]; f[n_] := Block[{k = n + 1}, While[PrimeQ@k || GCD[k, n] > 1, k++ ]; k]; Array[ f[ Composite[ # ]] &, 70] (* Robert G. Wilson v, Jan 12 2006 *)

Prog

(Python)
from sympy import isprime, gcd, composite
def A113496(n):
    m = composite(n)
    k = m+1
    while gcd(k, m) != 1 or isprime(k):
        k += 1
    return k # Chai Wah Wu, Mar 28 2021

Crossrefs

Cf. A002808, A113484.

Sequence in context: A050282 A096757 A101158 * A343670 A086531 A089091

Adjacent sequences: A113493 A113494 A113495 * A113497 A113498 A113499

Keyword

nonn

Author

Leroy Quet, Jan 11 2006

Extensions

More terms from Robert G. Wilson v, Jan 12 2006

Status

approved