1,2

(I). If p=(2*10^(3n+1)+7)/27 is prime then m=2p is in the sequence because m+phi(m)=3p-1=2*(10^(3n+1)-1)/9 is a repdigit number. m=2*(2*10^811+7)/27 (a 811-digit number) is the smallest such terms and the next such terms has 4219 digits. - Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 24 2006

(II). If p=(8*10^(3n+1)+1)/27 is prime then m=2p is in the sequence because m+phi(m)=8*(10^(3n+1)-1)/9 is a repdigit number. 5926 is the smallest such terms. - Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 24 2006

(III). If p=(2*10^n+1)/3 then both numbers 3p & 9p are in the sequence because 3p+phi(3p)=5p-2=3*(10^(n+1)-1)/9 & 9p+ phi(9p)=9*(10^(n+1)-1)/9 are repdigit numbers. 21 & 63 are the smallest such terms. - Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 24 2006

(IV). All primes p of the form (35*10^n+1)/9 are in the sequence because p+phi(p)=7*(10^n-1)/9 is a repdigit number. 389 is the smallest such terms. - Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 24 2006

(V). All primes p of the form (10^n+2)/6 are in the sequence because p+phi(p)=2p-1=3*(10^n-1)/9 is a repdigit number. 2, 17 & 167 are such terms. - Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 24 2006, Dec 19 2007

5185194+phi(5185194)=6666666.

Cf. A116017.

Sequence in context: A166098 A124365 A115896 this_sequence A048095 A031015 A024639

Adjacent sequences: A116015 A116016 A116017 this_sequence A116019 A116020 A116021

nonn,base

Giovanni Resta (g.resta(AT)iit.cnr.it), Feb 13 2006

More terms from Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 24 2006