A244438 Terms of the sequence A145749 which are not of the form 2*p where p is prime.

8, 188, 285, 902, 2013, 8493, 37406, 40977, 61918, 68210, 90094, 303853, 352941, 360446, 375565, 467654, 501693, 724934, 889285, 940093, 1079662, 1473565, 1488957, 1517206, 1573045, 1692302, 1864285, 2048973, 2077405, 2346226, 2584106, 2693517, 3393934, 3509997, 3802029, 4083526, 4194406

Offset: 1

Author

Farideh Firoozbakht, Aug 14 2014

Keywords

• nonn

Links

• Jens Kruse Andersen, Table of n, a(n) for n = 1..702

Crossrefs

Cf. A000010, A000203, A005384, A145749.

Programs

Mathematica

Select[Range[5000000], !PrimeQ[#/2] && DivisorSigma[1, #] + EulerPhi[#] == DivisorSigma[1, # + 1] + EulerPhi[# + 1] &]

PARI

for(n=1,10^7,s=eulerphi(n)+sigma(n);if(s==eulerphi(n+1)+sigma(n+1) && ((n%2==0 && !isprime(n/2)) || n%2),print1(n,", "))) \\ Derek Orr, Aug 14 2014