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A161551
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The smallest composite number larger than the n-th composite number, which has a sum of digits equal to the n-th composite number.
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2
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22, 15, 26, 18, 28, 39, 68, 69, 88, 99, 299, 399, 589, 699, 799, 899, 999, 2899, 3999, 5999, 6999, 7999, 9899, 9999, 29999, 39999, 58999, 69999, 89999, 99999, 299899, 399999, 499999, 689999, 699999, 889999, 999999, 1999999, 3899999, 3999999
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Variant of A073866, where the requirement that a(n) > A002808(n) is dropped.
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LINKS
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FORMULA
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EXAMPLE
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The first composite is 4, and the first sum of digits is 13, but since that is prime, we go to the next, 22, which being composite is a(1).
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MAPLE
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for j from n+1 do
end if;
end do:
end proc:
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PROG
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(UBASIC)
20 N=1
30 Q=str(N)
40 L=len(Q)
50 for X=1 to L
60 M=str(mid(Q, X, 1)): Z=Z+val(mid(Q, X, 1))
70 next X
80 if Z=56 and Z<>prmdiv(Z) and N<>prmdiv(N) then print N: stop
90 Z=0: N=N+1: goto 30
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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STATUS
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approved
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