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A078438
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a(n) = least positive integer solution k to h(k) = h(k-1)+h(k-2)+...+h(k-n), where h(n) is the length of n, f(n), f(f(n)), ...., 1 in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)
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OFFSET
| 1,1
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COMMENTS
| 1. Recall that f(n) = n/2 if n is even; = 3n + 1 if n is odd. 2. Problem: Is a(n) defined for all n, that is, does a positive integer solution k to h(n) = h(k-1)+h(k-2)+...+h(k-n) always exist?
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EXAMPLE
| k = 235 is the least k satisfying h(k) = h(k-1)+h(k-2)+h(k-3), so a(3) = 235.
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CROSSREFS
| Sequence in context: A168210 A206612 A160247 * A133723 A095389 A206611
Adjacent sequences: A078435 A078436 A078437 * A078439 A078440 A078441
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KEYWORD
| more,nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Dec 31 2002
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EXTENSIONS
| a(7) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 14 2010
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