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Search: id:A075681
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| 0, 0, 2, 21, 60, 121, 207, 321, 466, 645, 861, 1117, 1416, 1761, 2155, 2601, 3102, 3661, 4281, 4965, 5716, 6537, 7431, 8401, 9450, 10581, 11797, 13101, 14496, 15985, 17571, 19257, 21046, 22941, 24945, 27061, 29292, 31641, 34111, 36705
(list; graph; listen)
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OFFSET
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1,3
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LINKS
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Ed Pegg Jr., Pancakes
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FORMULA
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1/2*n^3+7/2*n^2-23n+25, for n>2. G.f.: (x^7-x^6-12x^5+13x^4+2x^3)/(1-x)^4. - Ralf Stephan (ralf(AT)ark.in-berlin.de), Mar 13 2003
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EXAMPLE
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4 gives 3*2*2*2=24. Prefix flips involving 4 flips give 3, hence a[4]=24-3=21.
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CROSSREFS
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Sequence in context: A042455 A074875 A097718 this_sequence A034520 A111128 A129556
Adjacent sequences: A075678 A075679 A075680 this_sequence A075682 A075683 A075684
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KEYWORD
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nonn
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AUTHOR
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Jon Perry (perry(AT)globalnet.co.uk), Oct 12 2002
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EXTENSIONS
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More terms from Ralf Stephan (ralf(AT)ark.in-berlin.de), Mar 13 2003
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