

A079394


Compare t(n) and t(n+1) where t = Ramanujan's tau function (A000594); a(n) = pq where p and q are given below.


0



21, 31, 21, 31, 21, 11, 31, 21, 11, 31, 22, 11, 32, 41, 42, 21, 32, 41, 22, 12, 11, 31, 41, 21, 32, 21, 32, 41, 22, 11, 11, 32, 41, 22, 31, 21, 11, 12, 31, 42, 42, 22, 11, 12, 12, 31, 42, 21, 32, 21, 32, 21, 31, 41, 22, 31, 21, 11, 12, 31, 42, 41, 41, 21, 11, 11, 32, 42, 42
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OFFSET

0,1


COMMENTS

p = 1 if t(n) < 0, t(n+1) < 0; p = 2 if t(n) >= 0, t(n+1) < 0; p = 3 if t(n) < 0, t(n+1) >= 0; p = 4 if t(n) >= 0, t(n+1) >= 0.
q = 1 if t(n) <= t(n+1); q = 2 if t(n) > t(n+1.


LINKS

Table of n, a(n) for n=0..68.


EXAMPLE

A000594(1)=1, A000594(2)=24. Hence the sign changes from + to  and the modulus increasing. Consulting the key, this gives a(1)=21.


PROG

(PARI) T(n)=n*(n+1)/2 rtau3(n)=local(y, j); y=0; j=1; while (T(j1)<n, j++); j; for (i=1, j, y=y(1)^i*(2*i1)*x^(T(i1))); y=y^8; polcoeff(y, n1) for (n=1, 100, r3=rtau3(n); r31=rtau3(n+1); rn=(sign(r3)+1)/2; rn1=sign(r31)+1; print1((rn+rn1+1)""(abs(r3)>abs(r31))+1", "))


CROSSREFS

Cf. A000594.
Sequence in context: A115433 A116096 A116116 * A112375 A067599 A261322
Adjacent sequences: A079391 A079392 A079393 * A079395 A079396 A079397


KEYWORD

nonn


AUTHOR

Jon Perry, Jan 06 2003


STATUS

approved



