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URL: https://oeis.org/A074755

⇱ A074755 - OEIS

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A074755
Number of n-digit non-leading-zero trimorphic numbers (m such that m^3 ends in m).
1
5, 7, 13, 11, 11, 13, 12, 13, 12, 13, 13, 11, 10, 12, 12, 13, 12, 12, 12, 11, 13, 12, 12, 10, 10, 13, 13, 13, 11, 13, 12, 10, 10, 11, 11, 13, 13, 10, 13, 11, 13, 12, 13, 12, 12, 13, 12, 12, 12, 12, 12, 11, 10, 10, 13, 13, 13, 13, 13, 13, 11, 13, 12, 10, 11, 11, 13
OFFSET
1,1
COMMENTS
For n >= 3, I can show 8 <= a(n) <= 13 and I highly suspect that 10 <= a(n) <= 13 from empirical evidence.
If n >= 3, there are 15 integers 0 <= x < 10^n with x == 0, 1 or -1 mod 5^n and x == 0, 1, -1, 2^(n-1)-1 or 2^(n-1)+1 mod 2^n, and a(n) is the number of these that are >= 10^(n-1). - Robert Israel, Jul 07 2014
LINKS
MAPLE
f:= n ->
nops(select(`>=`, {seq(seq(chrem([a, b], [2^n, 5^n]), a={0, 1, 2^(n-1)-1, 2^(n-1)+1, -1}), b={0, 1, -1})}, 10^(n-1))):
seq(f(n), n=1..100); # Robert Israel, Jul 07 2014
CROSSREFS
Cf. A033819.
Sequence in context: A088897 A255233 A361708 * A354200 A002659 A357938
KEYWORD
nonn,base
AUTHOR
David W. Wilson, Sep 28 2002
STATUS
approved