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 A100916 Sum of a semiprime and its semiprime index is a new semiprime. 4
 10, 15, 25, 34, 46, 51, 55, 57, 69, 86, 91, 95, 106, 119, 121, 133, 141, 145, 155, 161, 166, 217, 218, 226, 247, 249, 253, 262, 274, 291, 298, 299, 302, 305, 341, 358, 365, 382, 407, 413, 445, 446, 481, 485, 501, 515, 533, 538, 543, 551, 559, 614, 623, 626 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This is the semiprime analog of A061067. LINKS Eric Weisstein, World of Mathematics, Semiprime. FORMULA a(n) = A100466(n) - A100915(n) = A001358(A100915(n)). EXAMPLE a(1) = 10 because 10 = semiprime(4) and semiprime(4) + 4 = 14 is semiprime. a(2) = 15 because 15 = semiprime(6) and semiprime(6) + 6 = 21 is semiprime. MATHEMATICA Module[{sp=Select[Range[1000], PrimeOmega[#]==2&], len}, len=Length[sp]; Select[ Thread[{sp, Range[len]}], PrimeOmega[Total[#]]==2&]][[All, 1]] (* Harvey P. Dale, Jan 13 2019 *) CROSSREFS Cf. A001358, A061067, A100493, A100466, A100467, A100915. Sequence in context: A173477 A091022 A133372 * A001750 A231643 A276541 Adjacent sequences:  A100913 A100914 A100915 * A100917 A100918 A100919 KEYWORD easy,nonn AUTHOR Ray Chandler, Nov 26 2004 STATUS approved

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Last modified September 29 06:29 EDT 2020. Contains 337425 sequences. (Running on oeis4.)