OFFSET
1,1
COMMENTS
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..24814
EXAMPLE
PROG
(PARI)
isA071395(n) = if(sigma(n) <= 2*n, 0, fordiv(n, d, if((d != n)&&(sigma(d) >= 2*d), return(0))); (1)); \\ After code in A071395
isA006039(n) = ((sigma(n)==(2*n))||isA071395(n));
A337690(n) = sumdiv(n, d, isA006039(d));
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
isA337386(n) = { my(x=A003961(n)); (sigma(x)>=2*x); };
isA337479(n) = (isA337386(n)&&(1==sumdiv(n, d, isA337386(d))));
k=0; for(n=1, 2^15, if(isA337479(n), k++; print1(A337690(n), ", ")));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen and Peter Munn, Sep 20 2020
STATUS
approved