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A067499
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Powers of 2 with digit sum also a power of 2.
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13
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1, 2, 4, 8, 512, 68719476736, 38685626227668133590597632, 95780971304118053647396689196894323976171195136475136, 25108406941546723055343157692830665664409421777856138051584
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Question is the sequence finite or infinite?
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FORMULA
| a(n) = 2^k with digit sum a(n) = 2^r.
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EXAMPLE
| 512 = 2^9 and 5+1+2 = 8 = 2^3. 68719476736 = 2^36. sum of digits = 64 = 2^6
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MAPLE
| with(numtheory): pow2 := [2^i$ i=1..2000]: for n from 1 to 1000 do L1 := convert(2^n, base, 10): if member(sum(L1[i], i=1..nops(L1)), pow2) then printf(`%d, `, 2^n) fi: od: (Sellers)
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CROSSREFS
| Sequence in context: A082613 A013553 A061089 * A135212 A012456 A071686
Adjacent sequences: A067496 A067497 A067498 * A067500 A067501 A067502
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KEYWORD
| base,easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 19 2001
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 19 2001
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