A008331 a(n) = phi(prime(n)+1).
2, 2, 2, 4, 4, 6, 6, 8, 8, 8, 16, 18, 12, 20, 16, 18, 16, 30, 32, 24, 36, 32, 24, 24, 42, 32, 48, 36, 40, 36, 64, 40, 44, 48, 40, 72, 78, 80, 48, 56, 48, 72, 64, 96, 60, 80, 104, 96, 72, 88, 72, 64, 110, 72, 84, 80, 72, 128, 138, 92, 140, 84, 120, 96, 156, 104, 164, 156, 112, 120, 116
Offset: 1
Keywords
Links
- Michael De Vlieger, Table of n, a(n) for n = 1..10000
Programs
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Maple
for i from 1 to 500 do if isprime(i) then print(phi(i+1)); fi; od;
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Mathematica
EulerPhi[1 + Prime@ Range@ 71] (* Michael De Vlieger, Feb 17 2021 *)
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PARI
a(n) = eulerphi(prime(n)+1); \\ Michel Marcus, Feb 17 2021
Formula
Extensions
Offset 1 from Michel Marcus, Feb 17 2021