A063119 a(n) = sigma(a(n-1)) + phi(a(n-1)), a(1)=3.

3, 6, 14, 30, 80, 218, 438, 1032, 2976, 9024, 27328, 74512, 181646, 363294, 908268, 2422072, 5752432, 15203056, 39044504, 92788840, 252556992, 808096140, 2666717760, 10285934208, 33734451200, 97757260032, 293143652800

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..140

Mathematica

NestList[DivisorSigma[1, #]+EulerPhi[#]&, 3, 30] (* Harvey P. Dale, Feb 06 2020 *)

Prog

(PARI) seq(n)={my(v=vector(n)); v[1]=3; for(i=2, n, v[i]=sigma(v[i-1]) + eulerphi(v[i-1])); v} \\ Harry J. Smith, Aug 19 2009, Andrew Howroyd, Jun 26 2018

Crossrefs

Sequence in context: A077926 A091601 A339154 * A218982 A106803 A199853

Adjacent sequences: A063116 A063117 A063118 * A063120 A063121 A063122

Keyword

nonn

Author

Jason Earls, Aug 09 2001

Extensions

More terms from Harry J. Smith, Aug 19 2009

Status

approved