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A080151
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Let m = Demlo number A002477(n); a(n) = sum of digits of m.
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8
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1, 4, 9, 16, 25, 36, 49, 64, 81, 82, 85, 90, 97, 106, 117, 130, 145, 162, 163, 166, 171, 178, 187, 198, 211, 226, 243, 244, 247, 252, 259, 268, 279, 292, 307, 324, 325, 328, 333, 340, 349, 360, 373, 388, 405, 406, 409, 414, 421, 430, 441, 454, 469, 486, 487
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Also a(n) = sqrt(A080150(n)).
Record values in A003132: a(n) = A003132(A051885(n)). [Reinhard Zumkeller, Jul 10 2011]
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LINKS
| Eric Weisstein's World of Mathematics, Demlo Number
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FORMULA
| a(n)=(9^2)*(n/9-{n/9}+{n/9}^2)=81*(floor(x/9)+{x/9}^2), where the symbol {x} means fractional part of x. [From Barbarel Tres Mil (barbarel3000(AT)yahoo.es), Nov 22 2009]
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MATHEMATICA
| Contribution from Barbarel Tres Mil (barbarel3000(AT)yahoo.es), Nov 22 2009: (Start)
(by direct counting)
Repunit[n_] := (-1 + 10^n)/9;
A080151[n_]:=Plus @@ IntegerDigits[Repunit[n]^2];
(by the formula)
A080151[n_] := (9^2)*(n/9 - FractionalPart[n/9] + FractionalPart[n/9]^2)
(or alternatively) A080151[n_] := 81*(Floor[n/9]+ FractionalPart[n/9]^2) (End)
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CROSSREFS
| Cf. A080150, A002477, A080160, A080161, A080162.
Sequence in context: A061205 A048387 A035121 * A106545 A169920 A093837
Adjacent sequences: A080148 A080149 A080150 * A080152 A080153 A080154
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KEYWORD
| nonn,base
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AUTHOR
| Eric Weisstein (eric(AT)weisstein.com), Jan 31, 2003
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