A368991 Doudna-gram for nondeficient numbers; Partial sums of A368990.

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

Links

Antti Karttunen, Table of n, a(n) for n = 0..65537

Index entries for sequences related to sigma(n)

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. A005940, A023196, A294936, A324055.

Cf. also A368910, A368993.

Sequence in context: A093125 A226390 A156081 * A147954 A105047 A331135

Adjacent sequences: A368988 A368989 A368990 * A368992 A368993 A368994

Keyword

nonn

Author

Antti Karttunen, Jan 11 2024

Status

approved