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| A006893
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Smallest number whose representation requires n triangular numbers with greedy algorithm; also number of 1-2 rooted trees of height n.
(history;
published version)
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#60 by Joerg Arndt at Sat Aug 03 01:49:27 EDT 2024
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#59 by Michel Marcus at Sat Aug 03 01:21:26 EDT 2024
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#58 by Jason Yuen at Fri Aug 02 23:27:32 EDT 2024
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#57 by Jason Yuen at Fri Aug 02 23:27:17 EDT 2024
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| FORMULA
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a(0) = 1, a(n) = sum(Sum_{i=0..n-1, } t(a(i)), where t(n)=n*(n+1)/2. - Jon Perry, Feb 14 2004
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| KEYWORD
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nonn,easy
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| STATUS
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approved
editing
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#56 by Alois P. Heinz at Wed Sep 22 16:58:55 EDT 2021
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#55 by Michael De Vlieger at Wed Sep 22 16:19:33 EDT 2021
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#54 by Michael De Vlieger at Wed Sep 22 16:19:30 EDT 2021
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| LINKS
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Michael De Vlieger, <a href="/A006893/b006893.txt">Table of n, a(n) for n = 1..13</a>
Mee Seong Im and Can Ozan Oğuz, <a href="https://www.researchgate.net/publication/351823558_Natural_transformations_between_induction_and_restriction_on_iterated_wreath_product_of_symmetric_group_of_order_2">Natural transformations between induction and restriction on iterated wreath product of symmetric group of order 2</a>, (2021).
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| STATUS
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approved
editing
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#53 by Joerg Arndt at Tue Nov 17 05:48:05 EST 2020
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#52 by Joerg Arndt at Tue Nov 17 05:47:48 EST 2020
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| FORMULA
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a(0) = 1, a(n) = sum(i=0..n-1, t(a(i)), where t(n)=n*(n+1)/2. E.g., a(4) = t(1) + t(1) + t(2) + t(5) = 1 + 1 + 3 + 15 = 20. - Jon Perry, Feb 14 2004
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approved
editing
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#51 by Joerg Arndt at Tue Nov 17 05:46:31 EST 2020
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