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URL: https://oeis.org/A255385

⇱ A255385 - OEIS

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A255385
a(n) = sigma(n) + phi(n) - tau(n).
1
1, 2, 4, 6, 8, 10, 12, 15, 16, 18, 20, 26, 24, 26, 28, 34, 32, 39, 36, 44, 40, 42, 44, 60, 48, 50, 54, 62, 56, 72, 60, 73, 64, 66, 68, 94, 72, 74, 76, 98, 80, 100, 84, 98, 96, 90, 92, 130, 96, 107, 100, 116, 104, 130, 108, 136, 112, 114, 116, 172, 120, 122
OFFSET
1,2
COMMENTS
If n is prime or semiprime, then a(n) = 2n-2.
FORMULA
a(n) = A000203(n) + A000010(n) - A000005(n).
a(n) = 2n - 2 + A153011(n). - Omar E. Pol, May 20 2015
MAPLE
with(numtheory): A255385:=n->sigma(n)+phi(n)-tau(n): seq(A255385(n), n=1..100);
MATHEMATICA
Table[DivisorSigma[1, n] + EulerPhi[n] - DivisorSigma[0, n], {n, 100}]
PROG
(PARI) vector(100, n, sigma(n)+eulerphi(n)-numdiv(n)) \\ Derek Orr, May 05 2015
(Magma) [SumOfDivisors(n)+ EulerPhi(n)-NumberOfDivisors(n): n in [1..100]]; // Vincenzo Librandi, May 06 2015
CROSSREFS
Cf. A000005 (tau), A000010 (phi), A000203 (sigma).
Sequence in context: A140955 A386213 A111905 * A187412 A187473 A394988
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, May 05 2015
STATUS
approved