The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A326024 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A326024

Number of subsets of {1..n} containing no sums or products of distinct elements.
(history; published version)

#14 by Alois P. Heinz at Sat Apr 10 15:07:42 EDT 2021

STATUS

reviewed

approved

#13 by Michel Marcus at Sat Apr 10 14:51:14 EDT 2021

STATUS

proposed

reviewed

#12 by Fausto A. C. Cariboni at Sat Apr 10 14:50:37 EDT 2021

STATUS

editing

proposed

#11 by Fausto A. C. Cariboni at Sat Apr 10 14:50:12 EDT 2021

EXTENSIONS

Terms a(16) and beyond -a(40) from Andrew Howroyd, Aug 25 2019

#10 by Fausto A. C. Cariboni at Sat Apr 10 14:48:31 EDT 2021

LINKS

Fausto A. C. Cariboni, <a href="/A326024/b326024.txt">Table of n, a(n) for n = 0..80</a>

STATUS

approved

editing

#9 by Joerg Arndt at Mon Aug 26 01:44:27 EDT 2019

STATUS

reviewed

approved

#8 by Joerg Arndt at Mon Aug 26 01:44:10 EDT 2019

STATUS

proposed

reviewed

#7 by Andrew Howroyd at Sun Aug 25 21:03:06 EDT 2019

STATUS

editing

proposed

#6 by Andrew Howroyd at Sun Aug 25 20:51:52 EDT 2019

DATA

1, 2, 3, 5, 9, 15, 25, 41, 68, 109, 179, 284, 443, 681, 1062, 1587, 2440, 3638, 5443, 8021, 11953, 17273, 25578, 37001, 53953, 77429, 113063, 160636, 232928, 330775, 475380, 672056, 967831, 1359743, 1952235, 2743363, 3918401, 5495993, 7856134, 10984547, 15669741

PROG

(PARI)

a(n)={

my(recurse(k, es, ep)=

if(k > n, 1,

my(t = self()(k + 1, es, ep));

if(!bittest(es, k) && !bittest(ep, k),

es = bitor(es, bitand((2<<n)-1, es << k));

forstep(i=n\k, 1, -1, if(bittest(ep, i), ep=bitor(ep, 1<<(k*i))));

t += self()(k + 1, es, ep);

);

t);

);

1 + if(n, recurse(2, 1, 2));

} \\ Andrew Howroyd, Aug 25 2019

KEYWORD

nonn,more

nonn

EXTENSIONS

Terms a(16) and beyond from Andrew Howroyd, Aug 25 2019

STATUS

approved

editing

#5 by Susanna Cuyler at Wed Jul 10 07:34:52 EDT 2019

STATUS

proposed

approved