A113636 In the sequence of positive integers add 1 to each nonprime number.
2, 2, 3, 5, 5, 7, 7, 9, 10, 11, 11, 13, 13, 15, 16, 17, 17, 19, 19, 21, 22, 23, 23, 25, 26, 27, 28, 29, 29, 31, 31, 33, 34, 35, 36, 37, 37, 39, 40, 41, 41, 43, 43, 45, 46, 47, 47, 49, 50, 51, 52, 53, 53, 55, 56, 57, 58, 59, 59, 61, 61, 63, 64, 65, 66, 67, 67, 69, 70, 71, 71, 73
Offset: 1
Programs
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Mathematica
Array[# + Boole[! PrimeQ@ #] &, 72] (* Michael De Vlieger, Nov 05 2020 *)
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PARI
a(n) = if (!isprime(n), n+1, n); \\ Michel Marcus, Nov 06 2020
Formula
a(n) = A014684(n) + 1. - Bill McEachen, Nov 01 2020
From Wesley Ivan Hurt, Jun 21 2025: (Start)
a(n) = n + c(n), where c = A005171.
a(n) = Sum_{d|n} A380449(d) * mu(n/d). (End)
Extensions
Offset 1 from Michel Marcus, Nov 06 2020
Comments