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Search: id:A130843
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| A130843 |
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Numbers n for which a number m (m<n) exists such that n = Sum_digits[binomial(n,m)]. |
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+0
2
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| 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 13, 15, 16, 18, 21, 26, 27, 33, 36, 39, 42, 45, 48, 51, 52, 53, 54, 60, 63, 66, 67, 71, 72, 74, 75, 78, 79, 80, 81, 90, 99, 105, 108, 114, 117, 123, 124, 126, 127, 129, 134, 135, 141, 144, 150, 152, 153, 158, 159, 162, 171, 177, 180, 186
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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n=13 --> m=4 because binomial(13,4) = 13!/(4!*9!) = 715 --> 7+1+5 = 13
n=75 --> m=37 because binomial(75,37) = 75!/(37!*38!)=3446310324346630677300 --> 3+4+4+6+3+1+3+2+4+3+4+6+6+3+6+7+7+3 = 75
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MAPLE
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P:=proc(n) local i, j, k, w; for i from 1 by 1 to n do for j from 1 to i do w:=0; k:=binomial(i, j); while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; if i=w then print(i); break; fi; od; od; end: P(200);
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CROSSREFS
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Cf. A131382, A131417, A131418.
Sequence in context: A072618 A069784 A048097 this_sequence A087087 A050742 A111228
Adjacent sequences: A130840 A130841 A130842 this_sequence A130844 A130845 A130846
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KEYWORD
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easy,nonn,base
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Jul 20 2007
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