A305890 Filter sequence for all such sequences b, for which b(A176997(k)) = constant for all k > 1, where A176997 is the union of odd primes and Fermat pseudoprimes.

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 11, 12, 3, 13, 3, 14, 15, 16, 3, 17, 18, 19, 20, 21, 3, 22, 3, 23, 24, 25, 26, 27, 3, 28, 29, 30, 3, 31, 3, 32, 33, 34, 3, 35, 36, 37, 38, 39, 3, 40, 41, 42, 43, 44, 3, 45, 3, 46, 47, 48, 49, 50, 3, 51, 52, 53, 3, 54, 3, 55, 56, 57, 58, 59, 3, 60, 61, 62, 3, 63, 64, 65, 66, 67, 3, 68, 69, 70, 71, 72, 73, 74, 3

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..101101

Formula

For all i, j: A305801(i) = A305801(j) => a(i) = a(j) => A062173(i) = A062173(j).

Prog

(PARI)
up_to = 100000;
A257531(n) = if(n==1, 0, if(Mod(2, n)^(n-1)==1, 1, 0));
partialsums(f, up_to) = { my(v = vector(up_to), s=0); for(i=1, up_to, s += f(i); v[i] = s); (v); }
vpartsums = partialsums(A257531, up_to);
Apartsums(n) = vpartsums[n];
A305890(n) = if(n<=2, n, if(A257531(n), 3, 1+n-Apartsums(n)));

Crossrefs

Cf. A001567, A062173, A176997, A257531.

Differs from A305801 for the first time at n=341, where a(341) = 3, while A305801(341) = 275.

Sequence in context: A361021 A373980 A322973 * A305801 A075850 A327565

Adjacent sequences: A305887 A305888 A305889 * A305891 A305892 A305893

Keyword

nonn

Author

Antti Karttunen, Jul 01 2018

Status

approved