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A368910
Partial sums of A368909.
4
0, 1, 1, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 16, 16, 16, 17, 17, 18, 19, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21, 21
OFFSET
0,4
LINKS
FORMULA
a(0) = 0, and for n > 0, a(n) = a(n-1) + A368909(n), where A368909(n) = A003415(sigma(A005940(1+n))) mod 2.
PROG
(PARI)
up_to = 65537;
A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A368909(n) = (A003415(sigma(A005940(1+n)))%2);
A368910list(up_to) = { my(v=vector(up_to), s=A368909(0)); for(i=1, up_to, s +=
A368909(i); v[i] = s); (v); };
v368910 = A368910list(up_to);
A368910(n) = if(!n, A368909(0), v368910[n]);
CROSSREFS
Partial sums of A368909.
Cf. also A349909.
Sequence in context: A216256 A309407 A046693 * A196376 A156077 A189641
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 11 2024
STATUS
approved