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A368991
Doudna-gram for nondeficient numbers; Partial sums of A368990.
3
0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 17, 17, 18, 18, 18, 18, 19, 19, 20, 20, 20, 20, 20, 20, 20, 20, 21, 21, 22, 22, 22, 22, 23, 23, 24, 24, 25, 25, 25, 25, 26, 26, 27, 27, 28
OFFSET
0,12
FORMULA
a(0) = 0, and for n > 0, a(n) = a(n-1) + A368990(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); };
A294936(n) = (sigma(n)>=(2*n));
A368990(n) = A294936(A005940(1+n));
A368991list(up_to) = { my(v=vector(up_to), s=A368990(0)); for(i=1, up_to, s += A368990(i); v[i] = s); (v); };
v368991 = A368991list(up_to);
A368991(n) = if(!n, A368990(0), v368991[n]);
CROSSREFS
Partial sums of A368990.
Cf. also A368910, A368993.
Sequence in context: A093125 A226390 A156081 * A147954 A105047 A331135
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 11 2024
STATUS
approved