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Revision History for A337785 (Bold, blue-underlined text is an addition; faded, red-underlined text is a deletion.)

newer changes | Showing entries 11-20 | older changes
Number of addition triangles whose sum is n (version 1).
(history; published version)
#21 by Seiichi Manyama at Mon Sep 21 15:48:51 EDT 2020
CROSSREFS

Cf. A014430, A062684, A062896, A337765, A337766, see A337787 for version 2.

#20 by Seiichi Manyama at Mon Sep 21 15:48:02 EDT 2020
PROG

(Ruby)

def f(n, ary)

s = 0

n.times{|i|

s += ary.inject(:+)

ary = (1..n - 1 - i).map{|j| ary[j - 1] + ary[j]}

}

s

end

def A(n)

f_ary = (1..n - 1).map{|i| [i]}

cnt = 1

s = 1

while f_ary.size > 0

b_ary = []

f_ary.each{|i|

(1..i[0] - 1).each{|j|

a = [j]

(0..s - 1).each{|k|

num = i[k] - a[k]

if num > 0

a << num

else

break

end

}

if a.size == s + 1

sum = f(s + 1, a)

if sum < n

b_ary << a

elsif sum == n

cnt += 1

end

end

}

}

f_ary = b_ary

s += 1

end

cnt

end

def A337785(n)

(1..n).map{|i| A(i)}

end

p A337785(50)

STATUS

proposed

editing

#19 by Seiichi Manyama at Mon Sep 21 15:13:12 EDT 2020
STATUS

editing

proposed

#18 by Seiichi Manyama at Mon Sep 21 15:07:35 EDT 2020
CROSSREFS

Cf. A014430, A062684, A062896, see A337787 for version 2.

STATUS

proposed

editing

#17 by Seiichi Manyama at Mon Sep 21 14:12:43 EDT 2020
STATUS

editing

proposed

#16 by Seiichi Manyama at Mon Sep 21 13:24:18 EDT 2020
CROSSREFS

Cf. A062684, A062896, see A337787 for version 12.

#15 by Seiichi Manyama at Mon Sep 21 13:24:09 EDT 2020
CROSSREFS

Cf. A062684, A062896, see A337787 for version 1.

#14 by Seiichi Manyama at Mon Sep 21 13:21:36 EDT 2020
CROSSREFS
#13 by Seiichi Manyama at Mon Sep 21 13:19:47 EDT 2020
NAME

Number of addition triangles whose sum is n (version 1).

#12 by Seiichi Manyama at Mon Sep 21 13:02:14 EDT 2020
COMMENTS

Reversing the base counts as a different triangle.