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A266451 Semiprimes that are the sum of six consecutive semiprimes. 2
58, 91, 123, 142, 161, 205, 278, 473, 566, 614, 706, 718, 802, 838, 851, 889, 1079, 1211, 1226, 1238, 1262, 1286, 1385, 1415, 1633, 1714, 1819, 1891, 1945, 2005, 2123, 2147, 2194, 2217, 2327, 2374, 2427, 2563, 2594, 2653, 2771, 2815, 2854, 2947, 2987, 3118, 3133, 3151, 3199, 3214, 3305, 3379 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

58 = A001358(21) = A001358(1) + ... + A001358(6) = 4+6+9+10+14+15,

91 = A001358(31) = A001358(3) + ... + A001358(8) = 9+10+14+15+21+22.

MAPLE

N:= 10^4: # to get all terms where the 6 consecutive semiprimes <= N

P:= select(isprime, [2, seq(i, i=3..N/2, 2)]): nP:= nops(P):

SP:= NULL:

for i from 1 to nP do

  for j from 1 to nP while P[i]*P[j] <= N do od:

  SP:= SP, op(map(`*`, P[i], P[1..j-1]));

od:

SP:= sort(convert({SP}, list)): nSP:= nops(SP):

select(numtheory:-bigomega=2, [seq(convert(SP[i..i+5], `+`), i=1..nSP-5)]): # Robert Israel, Nov 19 2017

MATHEMATICA

Select[(Total[#] & /@ Partition[Select[Range[4, 9999], 2 == PrimeOmega[#] &], 6, 1]), 2 == PrimeOmega[#] &]

CROSSREFS

Cf. A001358, A092192, A131610, A158339, A254712.

Sequence in context: A039430 A043253 A044033 * A124680 A181462 A260603

Adjacent sequences:  A266448 A266449 A266450 * A266452 A266453 A266454

KEYWORD

nonn

AUTHOR

Zak Seidov, Dec 29 2015

STATUS

approved

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Last modified July 22 02:02 EDT 2019. Contains 325210 sequences. (Running on oeis4.)