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A230416
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The infinite trunk of factorial beanstalk (A219666) with reversed subsections.
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5
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0, 1, 5, 2, 23, 17, 12, 10, 7, 119, 109, 102, 97, 92, 85, 79, 74, 70, 63, 57, 52, 48, 46, 40, 35, 30, 28, 25, 719, 704, 693, 680, 670, 658, 648, 641, 630, 623, 612, 605, 597, 584, 574, 562, 552, 545, 534, 527, 516, 509, 501, 492, 486, 481, 476, 465, 455, 443
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OFFSET
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0,3
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COMMENTS
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Can be viewed also as an irregular table: after the initial zero on row 0, start each row n with (n!)-1 and subtract repeatedly the sum of factorial expansion digits (A034968) to get successive terms, until the number that has already been listed [which is always (n-1)!-1] is encountered, which is not listed second time, but instead, the current row is finished and the next row starts with ((n+1)!-1), with the same process repeated.
Contains the terms in the infinite trunk of factorial beanstalk (A219666) listed in partially reversed manner: after the initial zero each subsequence lists A219661(n) successive terms from A219666, descending from (n!)-1 downwards.
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LINKS
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FORMULA
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For n < 3, a(n) = (n+1)!-1, and for n >= 3, a(n) = (k+2)!-1 if A219651(a(n-1)) is of form k!-1, otherwise just A219651(a(n-1)).
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EXAMPLE
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This irregular table begins as:
0;
1;
5, 2;
23, 17, 12, 10, 7;
119, 109, 102, 97, 92, 85, 79, 74, 70, 63, 57, 52, 48, 46, 40, 35, 30, 28, 25;
...
After the initial zero (on row 0), each row n is A219661(n) elements long.
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PROG
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(Scheme, with Antti Karttunen's IntSeq-library for memoizing definec-macro)
(define (which_in_A000142? n) (and (> n 0) (let loop ((n n) (i 2)) (cond ((= 1 n) (- i 1)) ((not (zero? (modulo n i))) #f) (else (loop (/ n i) (1+ i)))))))
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CROSSREFS
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The rows are the initial portions of every (n!-1)th row in A219659.
Analogous sequence for binary system: A218616.
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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