A254248
Number of terms in A006285 (de Polignac numbers) less than 10^n.
Original entry on oeis.org
0, 1, 1, 18, 262, 3393, 39541, 421863, 4457974, 46853770, 482301801, 4931928485
Offset: 0
-
dePolignacQ[n_] := OddQ[n] && Module[{m = 2}, While[n > m + 1 && ! PrimeQ[n - m], m *= 2]; n <= m + 1]; seq[max_] := Module[{p = 10, c = 1, s = {0}}, Do[If[dePolignacQ[k], c++]; If[k == p, p *= 10; AppendTo[s, c]], {k, 5, 10^max}]; s]; seq[6] (* Amiram Eldar, Feb 04 2021 *)
A255971
Number of terms in A255967 less than 10^n.
Original entry on oeis.org
0, 1, 1, 1, 11, 168, 2356, 28321, 326831, 3678318, 39570252, 418509525
Offset: 0
-
isA255967(m) = if(!(m % 2), 0, my(pow = 2); while(pow < m && !isprime(m - pow) && !isprime(m + pow), pow *= 2); pow > m);
list(len) = {my(pow = 10, c = 0); print1(0, ", "); for(k = 1, 10^len, if(isA255967(k), c++); if(k == pow-1, print1(c, ", "); pow *= 10));} \\ Amiram Eldar, Jul 19 2025
A255816
Number of primes in A065381 less than 10^n.
Original entry on oeis.org
1, 1, 16, 130, 1246, 11577, 102613, 931944, 8573235, 78557819, 723625420, 6738938504
Offset: 1
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isA065381(p) = if(p == 2, 1, my(pow = 1); while(pow < p && !isprime(p - pow), pow *= 2); pow > p);
list(len) = {my(pow = 10, c = 0); forprime(p = 1, 10^len, if(p > pow, print1(c, ", "); pow *= 10); if(isA065381(p), c++));} \\ Amiram Eldar, Jul 19 2025
A256238
Number of primes in A256237 less than 10^n.
Original entry on oeis.org
0, 1, 6, 68, 847, 7963, 81327, 800270, 7836076
Offset: 3
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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 = 1000, c = 0); forprime(p = 1, 10^len, if(p > pow, print1(c, ", "); pow *= 10); if(isA256163(p), c++));} \\ Amiram Eldar, Jul 19 2025
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