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A113917
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Maximal element of Image^inf({ 2 }) under repeated base-n zero-split squaring.
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1
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OFFSET
| 2,1
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COMMENTS
| Define f_b(x) to be the set of base b numbers left after splitting x^2 at its zero digits and Image_b(S) = union_{x in S}{ { x } union f_b(S) }, then a(n) = max(Image_n^inf({ 2 }))
Conjecture: a(n) is finite for all n
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EXAMPLE
| f_10(29648) = { 4, 39, 879 } since 29648^2 = 879003904
a(8) = 4 since Image_8({ 2 }) = { 2, 4 } and f_8({ 2, 4 }) = { 2, 4 } and max({ 2, 4 }) is 4.
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CROSSREFS
| Cf. A113918.
Sequence in context: A108331 A162554 A167840 * A069793 A160299 A177188
Adjacent sequences: A113914 A113915 A113916 * A113918 A113919 A113920
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KEYWORD
| nonn,hard
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AUTHOR
| Hugo van der Sanden (hv(AT)crypt.org) extending a suggestion from David W. Wilson, Jan 31 2006
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