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A369384 The smallest number k that can be partitioned in n ways as the sum of two numbers from A020487. 1
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 (list; graph; refs; listen; history; text; internal format)
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
Sequence in context: A024200 A137625 A132412 * A342454 A009772 A179024
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

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Last modified July 19 17:03 EDT 2024. Contains 374410 sequences. (Running on oeis4.)