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a(n) = 3*A146085(n) - 2.
0

%I #5 Dec 09 2018 12:57:26

%S 1,10,19,82,91,100,163,172,181,730,739,748,811,820,829,892,901,910,

%T 1459,1468,1477,1540,1549,1558,1621,1630,1639,6562,6571,6580,6643,

%U 6652,6661,6724,6733,6742,7291,7300,7309,7372,7381,7390,7453,7462,7471,8020,8029,8038,8101,8110,8119

%N a(n) = 3*A146085(n) - 2.

%C Positive integers such that for every integer m==4 (mod 9) there exists a unique representation of m as a sum of the form a(l)+3a(s).

%o (PARI) isa(n) = {my(d=Vecrev(digits(n, 3)), k=3); while (k <= #d, if (d[k], return (0)); k += 2;); d[1] == 1;} \\ A146085

%o isok(n) = !((n+2) % 3) && isa((n+2)/3); \\ _Michel Marcus_, Dec 09 2018

%Y Cf. A146085, A146087, A145812, A145818.

%K nonn

%O 1,2

%A _Vladimir Shevelev_, Oct 27 2008

%E More terms from _Michel Marcus_, Dec 09 2018

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Last modified September 24 03:45 EDT 2024. Contains 376185 sequences. (Running on oeis4.)