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 A001092 Union of all numbers {p, q} where p and q are both primes or powers of primes and q = p+2. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 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]. PROG (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 CROSSREFS Cf. A053702, A074852. Sequence in context: A284288 A343983 A074583 * A327782 A000430 A166684 Adjacent sequences:  A001089 A001090 A001091 * A001093 A001094 A001095 KEYWORD nonn,easy AUTHOR EXTENSIONS Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 14 2001 STATUS approved

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Last modified May 9 17:48 EDT 2021. Contains 343742 sequences. (Running on oeis4.)