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A364799
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Triangular numbers that for some k >= 1 are also the sum of the first k odd primes.
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1
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3, 15, 1236378, 1454365, 3541791, 104856921, 2677839153, 3656187921870, 3973810409128, 1448587865213374600, 36691639282445615088081
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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15 is a term because 15 = 1 + 2 + 3 + 4 + 5 = 3 + 5 + 7.
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MATHEMATICA
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Select[Accumulate[Prime[Range[2, 1000000]]], IntegerQ[Sqrt[8 # + 1]] &]
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PROG
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(PARI) lista(nn) = my(s=0); forprime(p=3, nn, s+=p; if(ispolygonal(s, 3), print1(s, ", "))) \\ Jinyuan Wang, Aug 10 2023
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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