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A093349
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A 7-fractal "castle" starting with 0.
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3
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0, 1, 0, 1, 0, 1, 0, 7, 6, 7, 6, 7, 6, 7, 0, 1, 0, 1, 0, 1, 0, 7, 6, 7, 6, 7, 6, 7, 0, 1, 0, 1, 0, 1, 0, 7, 6, 7, 6, 7, 6, 7, 0, 1, 0, 1, 0, 1, 0, 49, 48, 49, 48, 49, 48, 49, 42, 43, 42, 43, 42, 43, 42, 49, 48, 49, 48, 49, 48, 49, 42, 43, 42, 43, 42, 43, 42, 49, 48, 49, 48, 49, 48, 49, 42, 43
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,8
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FORMULA
| a(1)=0 then a(n)=w(n)-a(n-w(n)) where w(n)=7^floor(log(n-1)/log(7))
a(n) = sum(i=1, n-1, (-1)^(i-1)*7^valuation(i, 7))
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PROG
| (PARI) a(n)=if(n<2, 0, 7^floor(log(n-1)/log(7))-a(n-7^floor(log(n-1)/log(7))))
(PARI) a(n)=-sum(i=1, n-1, (-1)^i*7^valuation(i, 7))
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CROSSREFS
| Cf. A093347, A093348
Sequence in context: A021570 A197687 A188943 * A020789 A153857 A093813
Adjacent sequences: A093346 A093347 A093348 * A093350 A093351 A093352
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 26 2004
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