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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
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
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.)