A384014 a(n) is the number of n-digit terms in A384013.
0, 1, 16, 108, 834, 6893, 58659, 510839, 4515301, 40477023, 366751460, 3352789726, 30877698604, 286159371452, 2666303391801, 24959756192476, 234610874384116, 2213224276178123, 20945897352118544, 198802912201260034, 1891788092230264832, 18044365524165259927, 172479703095316537972
Offset: 1
Links
- Tomás Oliveira e Silva, Tables of values of pi(x) and of pi2(x)
Programs
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Mathematica
a[1]:=0; a[n_]:=Module[{count=0},For[k=Prime[PrimePi[10^(n-1)]+1], k<=Prime[PrimePi[10^n-1]],k=NextPrime[k],If[Part[d=IntegerDigits[k],1]==Part[d,2],count++]]; count]; Array[a,7]
Extensions
a(11)-a(23) from David Radcliffe, May 17 2025