A139677
Estimate of the sum of twin prime pairs < 10^n = 4*Pi2(10^2n).
Original entry on oeis.org
32, 820, 24676, 1761248, 109650716, 7482340880, 543121286660, 41216742789192
Offset: 1
For n = 8, SumTP(8) = A118552(8) = 41205774636932. Pi2(16)= 10304185697298.
4*Pi2(16) = 41216742789192. This has an error of 0.00026...
A146536
Sum of the first 10^n twin primes.
Original entry on oeis.org
8, 908, 328184, 69004076, 11556327260, 1707243198956, 237064232862404, 31153163750203064, 3947120494191630260, 486665774050923191336, 58727077924563028184984
Offset: 0
The 10^0-th twin prime pair is (3,5). This adds up to 8, the first entry in the sequence.
The first 10^1 twin prime pairs are (3,5),(5,7),(11,13) (17,19),(29,31),(41,43),(59,61),(71,73),(101,103),(107,109). This adds up to 908, the second entry in the table.
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// See links.
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a(n)={my(k=10^n,s=k,q); forprime(p=3, oo, if(p==q+2, s+=q; k--; if(!k, return(2*s))); q=p)} \\ Andrew Howroyd, Oct 22 2023
A129697
Sum of isolated primes < 10^n.
Original entry on oeis.org
2, 577, 51896, 4009989, 345281974, 30126035380, 2657646397769, 238004015750349, 21505022353019864, 1960179022139638131, 180020101551309284879, 16639947666244921992434, 1546703841471331792075283, 144470014127904647017055666
Offset: 1
The sum of the isolated primes < 100 = 2+23+37+47+53+67+79+83+89+97 = 577, the second term of this sequence.
- Cino Hilliard, Sum Isolated Primes. [broken link]
- Cino Hilliard, Gcc code. [broken link]
- Cino Hilliard, Sum of Isolated primes, message 38 in seqfun Yahoo group, providing code for gcc (needs formatting to become compilable), Jun 5, 2007. [Cached copy]
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isoprimes(n) = { local(j,s,x); for(j=1,n, s=0; forprime(x=2,10^j, if(!isprime(x-2)&&!isprime(x+2),s+=x) ); print1(s", ") ) }
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