A076959
Number of primes between 3^n and 4^n.
Original entry on oeis.org
0, 2, 9, 32, 119, 435, 1573, 5695, 20773, 76057, 279850, 1033937, 3837070, 14296494, 53468768, 200673056, 755606952, 2853697709, 10807617884, 41036410818, 156186010430, 595759180892, 2277112205791, 8720036044777, 33451314673521, 128533154571957
Offset: 1
A117757
Number of primes between 4^n and 4^(n+1).
Original entry on oeis.org
2, 4, 12, 36, 118, 392, 1336, 4642, 16458, 59025, 213922, 781924, 2879938, 10673034, 39769185, 148880193, 559658890, 2111459404, 7991867657, 30336822624, 115457945437, 440455347499, 1683882372217, 6450190109521, 24752190739937, 95142124007068, 366264701294309, 1411989176124066
Offset: 0
a(1) = 4 since the primes 5, 7, 11 and 13 lie between 4 and 16.
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a:=proc(n) local ct,j: ct:=0: for j from 4^n to 4^(n+1) do if isprime(j)=true then ct:=ct+1 else fi: ct: od: end: seq(a(n),n=0..8); # execution takes hours - Emeric Deutsch, Apr 16 2006
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{ for(n=0,30, istrt=4^n ; iend=istrt*4 ; resul=0 ; forprime(p=istrt+1,iend, resul++ ; ) ; print1(resul,",") ; ) ; } \\ R. J. Mathar, Apr 21 2006
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a(n) = primepi(4^(n+1)) - primepi(4^n) \\ Michel Marcus, Jun 21 2013
More terms from Brian Kuehn (brk158(AT)psu.edu), Apr 19 2006
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