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A008331
a(n) = phi(prime(n)+1).
7
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
1,1
LINKS
FORMULA
a(n) = A000010(A008864(n)). - _Michel Marcus_, Feb 17 2021
MAPLE
for i from 1 to 500 do if isprime(i) then print(phi(i+1)); fi; od;
MATHEMATICA
EulerPhi[1 + Prime@ Range@ 71] (* _Michael De Vlieger_, Feb 17 2021 *)
PROG
(PARI) a(n) = eulerphi(prime(n)+1); \\ _Michel Marcus_, Feb 17 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
_N. J. A. Sloane_
EXTENSIONS
Offset 1 from _Michel Marcus_, Feb 17 2021
STATUS
approved