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A204878 Numbers that cannot be written as sum of perfect numbers. 3
1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 25, 26, 27, 29, 31, 32, 33, 35, 37, 38, 39, 41, 43, 44, 45, 47, 49, 50, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Complement of A204879; A097796(a(n)) = 0.
LINKS
Eric Weisstein's World of Mathematics, Perfect Number
Wikipedia, Perfect number
FORMULA
a(38+k) = 49+2k for all k>0 (up to occurrence of an odd perfect number, known to be > 10^300, if it exists). - M. F. Hasler, Feb 09 2012
PROG
(Haskell)
import Data.List (elemIndices)
a204878 n = a204878_list !! (n-1)
a204878_list = map (+ 1) $ elemIndices 0 a097796_list
CROSSREFS
Cf. A000396 (perfect numbers).
Sequence in context: A047253 A248910 A254278 * A037918 A043091 A031943
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jan 20 2012
STATUS
approved

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Last modified May 18 15:24 EDT 2024. Contains 372664 sequences. (Running on oeis4.)