login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A368993
Doudna-gram for A336547; Partial sums of A368992.
3
1, 2, 3, 4, 5, 6, 7, 8, 9, 9, 9, 10, 11, 12, 13, 14, 15, 16, 16, 17, 17, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 28, 28, 29, 29, 29, 30, 30, 30, 30, 30, 30, 31, 31, 31, 32, 33, 33, 34, 35, 35, 36, 37, 38, 39, 39, 39, 40, 41, 42, 43, 44, 45, 46, 46, 47, 47, 47, 48, 49, 49, 49, 49, 49, 50, 51, 51, 52, 52, 52
OFFSET
0,2
FORMULA
a(0) = 0, and for n > 0, a(n) = a(n-1) + A368992(n).
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); };
A336546(n) = { my(f=factor(n)); (sigma(n)==lcm(vector(#f~, k, sigma(f[k, 1]^f[k, 2])))); };
A368992(n) = A336546(A005940(1+n));
A368993list(up_to) = { my(v=vector(up_to), s=A368992(0)); for(i=1, up_to, s += A368992(i); v[i] = s); (v); };
v368993 = A368993list(up_to);
A368993(n) = if(!n, A368992(0), v368993[n]);
CROSSREFS
Partial sums of A368992.
Cf. also A368910, A368991.
Sequence in context: A285762 A185137 A368906 * A137180 A258632 A263283
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 11 2024
STATUS
approved