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Search: id:A129731
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| A129731 |
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Each term is the previous term times the number of letters in the previous number, as conventionally spelled out in English. |
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+0
1
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| 1, 3, 15, 105, 1470, 42630, 1364160, 75028800, 3676411200, 272054428800
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Multiplicative analogue of A060403.
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FORMULA
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a(0) = 1; a(n+1) = a(n) * A005589(a(n)). a(0) = 1; a(n+1) = PRODUCT[i=1..n] A005589(a(i)).
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EXAMPLE
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a(1) = 1.
a(2) = 1 * A060403(1) = 1 * LettersIn("one") = 1*3 = 3.
a(3) = 3 * A060403(2) = 3 * LettersIn("three") = 3*5 = 15.
a(4) = 15 * A060403(3) = 15 * LettersIn("fifteen") = 15*7 = 105.
a(10) = 74 * A060403(a(9)) = 74 * LettersIn("three billion six hundred seventysix million four hundred eleven thousand two hundred") = 1364160 * 55 * 49 * 74 = 272054 28800 = 2^7 * 3 * 5^2 * 7^4 * 11 * 29 * 37.
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CROSSREFS
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Cf. A005589, A060403.
Sequence in context: A118750 A070826 A048599 this_sequence A088109 A128276 A107878
Adjacent sequences: A129728 A129729 A129730 this_sequence A129732 A129733 A129734
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KEYWORD
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easy,more,nonn,word,dumb,less,fini
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), May 12 2007, May 22 2007
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