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A113724
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A variant of Golomb's sequence using even numbers: a(n) is the number of times 2*n+2 occurs, starting with a(1) = 2.
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3
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2, 4, 4, 6, 6, 6, 6, 8, 8, 8, 8, 10, 10, 10, 10, 10, 10, 12, 12, 12, 12, 12, 12, 14, 14, 14, 14, 14, 14, 16, 16, 16, 16, 16, 16, 18, 18, 18, 18, 18, 18, 18, 18, 20, 20, 20, 20, 20, 20, 20, 20, 22, 22, 22, 22, 22, 22, 22, 22, 24, 24, 24, 24, 24, 24, 24, 24, 26, 26, 26, 26, 26, 26
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OFFSET
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1,1
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COMMENTS
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a(n) is taken to be the smallest number >= a(n-1) which is compatible with the description.
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LINKS
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EXAMPLE
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Start with 2 in row 1 and form a triangle where row n is generated from row n-1 by the rule given in the description. Then row 2 will have (2) 4's, row 3 will have (4) 6's and (4) 8's, etc.
The triangle begins:
2;
4,4;
6,6,6,6,8,8,8,8; ...
The number of terms in each row (also row sums with offset) is given by A113725: [1,2,8,56,984,87848,115679160,...].
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PROG
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(PARI) a=[2, 4, 4]; for(n=2, 20, for(i=1, a[n], a=concat(a, 2*n+2))); a
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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