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A216392
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Number of values of k for which sigma(k) is a permutation of decimal digits of k, for k < 2^n.
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0
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1, 1, 1, 1, 1, 1, 2, 2, 5, 7, 7, 13, 16, 21, 35, 57, 83, 143, 207, 278, 457, 790, 1064, 1815, 3468, 5194, 8226
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OFFSET
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1,7
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LINKS
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FORMULA
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EXAMPLE
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a(10) = 7 because the values of k satisfying the condition for k < 2^10 are {1, 69, 258, 270, 276, 609, 639}. - V. Raman, Feb 18 2014
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PROG
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(PARI) a(n)=sum(k=1, 2^n, vecsort(digits(k)) == vecsort(digits(sigma(k)))) \\ V. Raman, Feb 18 2014, based on edits by M. F. Hasler
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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STATUS
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approved
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