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A068524
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a(1) = 2; for n > 1, a(n) = largest prime not exceeding a(1) + ... + a(n-1).
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2
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2, 2, 3, 7, 13, 23, 47, 97, 193, 383, 769, 1531, 3067, 6133, 12269, 24533, 49069, 98129, 196247, 392503, 785017, 1570007, 3140041, 6280067, 12560147, 25120289, 50240587, 100481167, 200962327, 401924639, 803849303, 1607698583, 3215397193
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| a(4) = largest prime not exceeding a(3) + a(2) + a(1) = 3 + 2 + 2 = 7; so a(4) = 7.
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MATHEMATICA
| s={2}; ss=2; Do[a=If[PrimeQ[ss], ss, Prime[PrimePi[ss]]]; AppendTo[s, a]; AddTo[ss, a], {i, 40}]; A068524=s - Zak Seidov (zakseidov(AT)yahoo.com), Sep 10 2005
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PROG
| (PARI) /* Version 2.1.5 of PARI uses Pocklington-Lehmer to certify primality */ /* of a_n when 1 is used as the optional flag in isprime: isprime(a_n, 1) */ {a1=2; a2=2; print1(a1, ", ", a2, ", "); s=a1+a2; for(n=3, 40, a_n=precprime(s); if(isprime(a_n, 1), print1(a_n, ", "); s=s+a_n, error("very unlikely event occurred: ", a_n, " is a strong pseudoprime to up to 10 randomly-chosen bases but is not prime")))} (Rick L. Shepherd)
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CROSSREFS
| Sequence in context: A153940 A049905 A167348 * A184841 A109277 A093437
Adjacent sequences: A068521 A068522 A068523 * A068525 A068526 A068527
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KEYWORD
| nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Mar 21 2002
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EXTENSIONS
| More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jun 15 2004
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