A369384 The smallest number k that can be partitioned in n ways as the sum of two numbers from A020487.

1, 2, 29, 181, 442, 425, 850, 1300, 2600, 3250, 5525, 11050, 17425, 16900, 44100, 18850, 72250, 44200, 122525, 75400, 55250, 110500, 237250, 188500, 266500, 397800, 375700, 377000, 187850, 221000, 469625, 718250, 640900, 1105000, 1812200, 2340900, 751400, 3591250

Offset

0,2

Links

Michael S. Branicky, Table of n, a(n) for n = 0..106

Example

a(0) = 1 because 1 cannot be written as the sum of two terms in A020487.
2 = 1 + 1 = A020487(1) + A020487(1), so a(1) = 2.
The numbers 3, 4, ..., 28 can be written as the sum of two terms in A020487 in at most one way and 29 = 4 + 25 = A020487(2) + A020487(6) and 29 = 9 + 20 = A020487(3) + A020487(5), so a(2) = 29.

Prog

(Magma) ant:=func<n|IsZero(DivisorSigma(2, n) mod DivisorSigma(1, n))>; b:=[n: n in [1..700000] |ant(n)]; a:=[]; for n in [0..30] do k:=1; while #RestrictedPartitions(k, 2, Set(b)) ne n do k:=k+1; end while; Append(~a, k); end for; a;

Crossrefs

Cf. A000203, A001157, A020487.

Sequence in context: A024200 A137625 A132412 * A342454 A009772 A179024

Adjacent sequences: A369381 A369382 A369383 * A369385 A369386 A369387

Keyword

nonn

Author

Marius A. Burtea, Jan 25 2024

Extensions

a(16) corrected and more terms from Michael S. Branicky, Feb 24 2024

Status

approved