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A081751 a(n) is the smallest number that is precisely n-tuply abundant. 0
12, 24, 78, 66, 54, 42, 30, 120, 540, 390, 264, 282, 366, 180, 546, 510, 330, 318, 990, 936, 702, 780, 564, 1290, 870, 528, 312, 168, 222, 150, 138, 5778, 6174, 3432, 3150, 2850, 2190, 8432, 4464, 3472, 2480, 1488, 5430, 6750, 4452, 4396, 4650, 3270, 2712 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
See A081705 for the definition of n-tuply abundant. - David Wasserman, Jun 24 2004
LINKS
EXAMPLE
a(3)=78 because 78 is the smallest number that is exactly triply abundant, with this aliquot chain: 78->90->144->259->45.
PROG
(PARI) LIMIT = 50; A = vector(LIMIT); count = 0; i = 1; while (count < LIMIT, i = i + 1; ab = 0; lastn = i; n = sigma(i) - i; while(ab <= LIMIT && n > lastn, ab = ab + 1; lastn = n; n = sigma(lastn) - n); if(ab <= LIMIT && ab > 0 && A[ab] == 0, A[ab] = i; count = count + 1)); A \\ David Wasserman, Jun 24 2004
CROSSREFS
Sequence in context: A239635 A001041 A216425 * A120360 A120356 A109745
KEYWORD
nonn
AUTHOR
Gabriel Cunningham (gcasey(AT)mit.edu), Apr 08 2003
EXTENSIONS
More terms from David Wasserman, Jun 24 2004
STATUS
approved

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Last modified March 29 10:59 EDT 2024. Contains 371277 sequences. (Running on oeis4.)