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Search: id:A138124
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| A138124 |
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Initial digit of n-th even superperfect number A061652(n). |
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+0
5
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| 2, 4, 1, 6, 4, 6, 2, 1, 1, 3, 8, 8, 3, 2, 5, 7, 2, 1, 9, 1, 2, 1, 1, 2, 2, 2, 4, 2, 2, 2, 3, 8, 6, 2, 4, 3, 6, 2, 4
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also, initial digit of n-th superperfect number A019279(n), if there are no odd superperfect numbers.
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EXAMPLE
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a(5)=4 because the 5th even superperfect number A061652(5) is 4096 and the initial digit of 4096 is 4.
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MATHEMATICA
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lst = {2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, 3217, 4253, 4423, 9689, 9941, 11213, 19937, 21701, 23209, 44497, 86243, 110503, 132049, 216091, 756839, 859433, 1257787, 1398269, 2976221, 3021377, 6972593, 13466917}; f[n_] := Block[{pn = 2^(n - 1)}, Quotient[pn, 10^Floor[Log[10, pn]]]]; f@# & /@ - [From Robert G. Wilson v, <rgwv(AT)(AT)rgwv.com>, Apr 01 2008].
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CROSSREFS
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Cf. A000030, A077648, A019279, A061652, A135613, A135617, A138125.
Sequence in context: A081879 A066248 A065164 this_sequence A128860 A019680 A080032
Adjacent sequences: A138121 A138122 A138123 this_sequence A138125 A138126 A138127
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KEYWORD
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base,nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com) and Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 01 2008.
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EXTENSIONS
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More terms (a(13)-a(39)) from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 01 2008.
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