A001092 Union of all numbers {p, q} where p and q are both primes or powers of primes and q = p+2.
1, 2, 3, 4, 5, 7, 9, 11, 13, 17, 19, 23, 25, 27, 29, 31, 41, 43, 47, 49, 59, 61, 71, 73, 79, 81, 83, 101, 103, 107, 109, 125, 127, 137, 139, 149, 151, 167, 169, 179, 181, 191, 193, 197, 199, 227, 229, 239, 241, 243, 269, 271, 281, 283, 311, 313, 347, 349, 359
Offset: 1
References
- M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 844.
Links
- T. D. Noe, Table of n, a(n) for n = 1..10000
- M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
Programs
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PARI
{isprimepower(n)=matsize(factor(n))[1]==1} for(n=1,400,if(isprimepower(n)&&(isprimepower(n-2)||isprimepower(n+2)),print1(n","))) \\ Ralf Stephan, Aug 20 2004
Extensions
Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 14 2001