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 A108183 Primes equal to the sum of two successive semiprimes. 3
 19, 29, 43, 47, 59, 67, 73, 127, 151, 167, 173, 233, 283, 313, 317, 461, 521, 541, 593, 653, 701, 719, 727, 787, 839, 907, 967, 1249, 1409, 1439, 1471, 1549, 1601, 1831, 1867, 1873, 1913, 1993, 2029, 2083, 2089, 2287, 2311, 2351, 2393, 2579, 2593, 2693 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes p such that p = sum of n-th and (n+1)-st semiprimes for some n. Primes appearing in A109404. LINKS Zak Seidov, Table of n, a(n) for n = 1..10000 EXAMPLE 19 = sp(3) + sp(4) = 9 + 10 where sp(n) = n-th semiprime. 29 is a member because 2*7 + 3*5 = 29. 13 is not a member because although 2*2 + 3*3 = 13, 4 and 9 are not successive semiprimes. MATHEMATICA Select[ Plus @@@ Partition[ Select[ Range[1250], Plus @@ Last /@ FactorInteger[ # ] == 2 &], 2, 1], PrimeQ[ # ] &] (* Robert G. Wilson v, Jun 14 2005 *) Select[Total/@Partition[Select[Range[1500], PrimeOmega[#]==2&], 2, 1], PrimeQ] (* Harvey P. Dale, Nov 15 2013 *) CROSSREFS Cf. A109404. Sequence in context: A240724 A274849 A276049 * A157483 A173966 A096218 Adjacent sequences: A108180 A108181 A108182 * A108184 A108185 A108186 KEYWORD easy,nonn AUTHOR Giovanni Teofilatto, Jun 14 2005 EXTENSIONS Corrected and extended by Robert G. Wilson v, Jun 14 2005 Edited by N. J. A. Sloane, May 03 2007 STATUS approved

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Last modified April 17 13:58 EDT 2024. Contains 371764 sequences. (Running on oeis4.)