A088490 a(n) is the absolute value of p minus A004086(p), where (p-2,p) is the n-th pair of twin primes.
0, 0, 18, 72, 18, 9, 45, 36, 198, 792, 792, 0, 0, 198, 792, 693, 99, 99, 99, 0, 594, 297, 99, 99, 198, 396, 495, 297, 297, 495, 693, 495, 99, 99, 495, 180, 2268, 450, 2538, 2808, 2358, 90, 8442, 630, 1728, 90, 7812, 2088, 2358, 8352, 7452, 360
Offset: 1
Examples
The 4th pair of twin primes is (17,19). a(4) then is the absolute value of 19 - 91, which is 72.
Programs
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Mathematica
a = {}; For[n = 1, n < 275, n++, If[Prime[n + 1] == Prime[n] + 2, AppendTo[a, Abs[Prime[n + 1] - FromDigits[Reverse[IntegerDigits[Prime[n + 1]]]]]]]]; a -
PARI
revdifftp2(n) = { forprime(x=1,n, if(isprime(x+2), a=vector(x); x1=x+2; z=0; ln=length(Str(x1)); for(y=1,ln, a[y] = x1%10; x1=floor(x1/10); ); for(y=1,ln, z += a[y]*10^(ln-y); ); print1(abs(z-(x+2))" "); ) ) }
Extensions
Edited by Stefan Steinerberger, Jul 22 2007
Comments