VOOZH about

URL: https://oeis.org/A113496

⇱ A113496 - OEIS

login
A113496
a(n) = smallest composite integer > c(n) and coprime to c(n), where c(n) is the n-th composite integer.
4
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
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
Sequence in context: A050282 A096757 A101158 * A343670 A086531 A089091
KEYWORD
nonn
AUTHOR
Leroy Quet, Jan 11 2006
EXTENSIONS
More terms from Robert G. Wilson v, Jan 12 2006
STATUS
approved