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a(n) = Sum_{d|n} (0==1-A283991(d)).

a(n) = 1 + A294892(n) - A283991(n). ...).

Cf. also A294884, A294904.

For n=25, with divisors [1, 5, 25], both B(5,x) and B(25,x) are irreducible, so only 1 is counted and a(25)=1.

Differs from A033273 for the first time at n=25.

Antti Karttunen, <a href="/A294894/b294894.txt">Table of n, a(n) for n = 1..22001</a>

Cf. A186891, A283991, A294891, A294892, A294893.

Cf. also A294884.

allocatedNumber of divisors d of n such that either d=1 or Stern forpolynomial AnttiB(d,x) is Karttunenreducible.

1, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 4, 1, 2, 2, 4, 1, 4, 1, 4, 2, 2, 1, 6, 1, 2, 3, 4, 1, 5, 1, 5, 2, 2, 2, 7, 1, 2, 2, 6, 1, 5, 1, 4, 4, 2, 1, 8, 2, 3, 2, 4, 1, 6, 1, 6, 2, 2, 1, 9, 1, 2, 4, 6, 1, 5, 1, 4, 2, 5, 1, 10, 1, 2, 3, 4, 1, 5, 1, 8, 4, 2, 1, 9, 2, 2, 2, 6, 1, 9, 1, 4, 2, 2, 1, 10, 1, 4, 4, 6, 1, 5, 1, 6, 5

1,4

a(n) = Sum_{d|n} (0==A283991(d)).

a(n) + A294893(n) = A000005(n).

a(n) = 1 + A294892(n) - A283991(n). ...

(PARI)

ps(n) = if(n<2, n, if(n%2, ps(n\2)+ps(n\2+1), 'x*ps(n\2)));

A283991(n) = polisirreducible(ps(n));

A294894(n) = sumdiv(n, d, (0==A283991(d)));

Differs from A033273 for the first time at n=

allocated

nonn

Antti Karttunen, Nov 10 2017

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