This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
f[p_, e_] := (p^(e+1)-2*p+1)/(p-1); r[1] = 1; r[n_] := (Times @@ f @@@ FactorInteger[n])/n; Select[r /@ Range[10^5], IntegerQ] (* Amiram Eldar, Jul 07 2022 *)
A049060(n)={ local(i,resul,rmax,p) ; if(n==1, return(1) ) ; i=factor(n) ; rmax=matsize(i)[1] ; resul=1 ; for(r=1,rmax, p=0 ; for(j=1,i[r,2], p += i[r,1]^j ; ) ; resul *= p-1 ; ) ; return(resul) ; } isA051152(r)={ local(s,t) ; s=A049060(r) ; t=A049060(s) ; if( r == t && s !=r, return(1), return(0) ) ; } { for(n=1,30000000, if( isA051152(n), print(n," ") ) ; ) ; } \\ R. J. Mathar, Oct 12 2006
A049060(n)={ local(i,resul,rmax,p) ; if(n==1, return(1) ) ; i=factor(n) ; rmax=matsize(i)[1] ; resul=1 ; for(r=1,rmax, p=0 ; for(j=1,i[r,2], p += i[r,1]^j ; ) ; resul *= p-1 ; ) ; return(resul) ; } isA051153(r)={ local(s,t) ; s=A049060(r) ; t=A049060(s) ; if( 2*r == t, return(1), return(0) ) ; } { for(n=1,30000000, if( isA051153(n), print(n,",") ) ; ) ; } \\ R. J. Mathar, Oct 12 2006
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