OFFSET
1,12
COMMENTS
Scatterplot of this sequence shows interesting strata. - Antti Karttunen, Jan 22 2020
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
FORMULA
MATHEMATICA
t=Table[PrimePi[DivisorSigma[1, w]-EulerPhi[w]]- (PrimePi[DivisorSigma[1, w]]-PrimePi[EulerPhi[w]]), {w, 1, 10000}]
PROG
(PARI) A085122(n) = (primepi(sigma(n)-eulerphi(n)) - (primepi(sigma(n))-primepi(eulerphi(n)))); \\ Antti Karttunen, Jan 22 2020
CROSSREFS
KEYWORD
sign,look
AUTHOR
Labos Elemer, Jul 11 2003
EXTENSIONS
Name edited by Antti Karttunen, Jan 22 2020
STATUS
approved