OFFSET
1,1
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..269
EXAMPLE
48 is included as 48 = 15+33, and 15' * 33' = 8*14 = 112 = 48' = A003415(48).
1728 (= 2^6 * 3^3) is included as 1728 = 4+1724, and 4' * 1724' = 4*1728 = 6912 = 1728'.
3627 is included as 3627 = 38+3589, and 38' * 3589' = 21*134 = 2814 = 3627'.
PROG
(PARI)
up_to = 2^18;
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
v003415 = vector(up_to, n, A003415(n));
isA370126(n) = { my(z=v003415[n]); for(x=2, ceil(n/2), if(!isprime(x) && !isprime(n-x) && !(z%v003415[x]), if(z==v003415[x]*v003415[n-x], return(1)))); (0); }; \\ Antti Karttunen, Feb 22 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 21 2024
STATUS
approved