A379000 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = 0 if n is prime > 5, with f(n) = n for all other n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 7, 11, 7, 12, 13, 14, 7, 15, 7, 16, 17, 18, 7, 19, 20, 21, 22, 23, 7, 24, 7, 25, 26, 27, 28, 29, 7, 30, 31, 32, 7, 33, 7, 34, 35, 36, 7, 37, 38, 39, 40, 41, 7, 42, 43, 44, 45, 46, 7, 47, 7, 48, 49, 50, 51, 52, 7, 53, 54, 55, 7, 56, 7, 57, 58, 59, 60, 61, 7, 62, 63, 64, 7, 65, 66, 67, 68, 69, 7, 70, 71, 72, 73, 74, 75, 76, 7, 77, 78, 79, 7

Offset: 1

Author

Antti Karttunen, Dec 15 2024

Keywords

• nonn

Comments

For all i, j:

a(i) = a(j) => A305900(i) = A305900(j) => A305801(i) = A305801(j) => A305800(i) = A305800(j),

a(i) = a(j) => A379001(i) = A379001(j) => A379002(i) = A379002(j),

a(i) = a(j) => A379005(i) = A379005(j).

Links

• Antti Karttunen, Table of n, a(n) for n = 1..100000

Crossrefs

Cf. A000720.

Cf. A112765, A305800, A305801, A305900, A379001, A379002, A379005.

Programs

PARI

A379000(n) = if(n<=7, n, if(isprime(n), 7, 4+n-primepi(n)));

Formula

For n < 7, a(n) = n, for primes > 5, a(n) = 7, and for composite n > 7, a(n) = 4+n-A000720(n).