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A103394 Semiprimes in A103374. 2
4, 9, 15, 21, 33, 38, 58, 65, 86, 106, 121, 129, 265, 979, 1079, 2279, 7985, 8491, 14019, 15397, 37606, 61289, 71845, 117013, 127401, 196763, 221905, 244414, 265358, 290111, 466319, 555469, 1065241, 1672598, 4276487, 4712791, 5266246, 8178897 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

61289 is an element of this sequence because A103374(107) = 61289 and 61289 is semiprime because 61289 = 167 * 367 where both 167 and 367 are primes.

MATHEMATICA

SemiprimeQ[n_] := Plus @@ FactorInteger[n][[All, 2]] == 2; k = 6; Do[a[n] = 1, {n, k + 1}]; a[n_] := a[n] = a[n - k] + a[n - k - 1]; Union[Select[Array[a, 160], SemiprimeQ]]

CROSSREFS

Intersection of A103374 with A001358.

Cf. A001358, A103374, A103384, A103392-A103401.

Sequence in context: A103399 A103398 A103397 * A103395 A103393 A103392

Adjacent sequences:  A103391 A103392 A103393 * A103395 A103396 A103397

KEYWORD

nonn,easy

AUTHOR

Jonathan Vos Post, Feb 03 2005

EXTENSIONS

Edited and extended by Ray Chandler and Robert G. Wilson v, Feb 06 2005

STATUS

approved

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Last modified May 7 16:00 EDT 2021. Contains 343652 sequences. (Running on oeis4.)