A256164 Number of terms in A256163 less than 10^n.

0, 1, 1, 1, 3, 10, 161, 2342, 27216, 317155, 3505277, 38127106

Offset

0,5

Links

Table of n, a(n) for n=0..11.

Prog

(PARI) isA256163(m) = if(!(m % 2), 0, my(pow = 2); while(pow < m && !isprime(m - pow) && !isprime(m + pow) && !isprime(m*pow - 1) && !isprime(m*pow + 1), pow *= 2); pow > m);
list(len) = {my(pow = 10, c = 0); print1(0, ", "); for(k = 1, 10^len, if(isA256163(k), c++); if(k == pow-1, print1(c, ", "); pow *= 10)); } \\ Amiram Eldar, Jul 19 2025

Crossrefs

Cf. A254248, A255816, A255971, A256163, A256238.

Sequence in context: A358949 A067999 A375529 * A270553 A308657 A156193

Adjacent sequences: A256161 A256162 A256163 * A256165 A256166 A256167

Keyword

nonn,more

Author

Arkadiusz Wesolowski, Mar 17 2015

Extensions

a(9)-a(11) from Amiram Eldar, Jul 19 2025

Status

approved