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a(n) is the number of k values for which A023193(k) = n.
3

%I #19 Aug 10 2024 01:29:45

%S 2,4,2,4,4,4,6,4,2,4,6,6,2,6,4,6,4,6,4,4,6,4,6,10,4,6,6,4,6,4,6,6,4,2,

%T 4,6,8,6,4,2,8,4,10,2,4,10,10,4,6,6,2,10,6,2,6,4,6,12,4,6,10,4,6,6,6,

%U 8,6,10,4,8,6,6,2,6,12,10,2,4,6,6,8,4,2,10,8,6,6,4,8,10,2,6,4,2

%N a(n) is the number of k values for which A023193(k) = n.

%C The old name was: "Schinzel's rhobar(n), number of distinct lengths of a block of consecutive integers on which a maximum of n primes occurs infinitely often (under the k-tuple conjecture)." [Note that "rhobar" is A023193.]

%D Computed by _Achim Flammenkamp_.

%e A block of 21 through 26 consecutive integers may contain at most 7 primes infinitely often. There are 6 possible lengths (21 through 26), so rhobar(7) = 6.

%Y First differences of A020497. Cf. A008407, A023193.

%K nonn

%O 1,1

%A _David W. Wilson_

%E Definition corrected by _Wolfdieter Lang_, Oct 07 2017