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A176658
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Numbers k such that semiprime(semiprime(k)) + 1 = semiprime(semiprime(k+1)).
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0
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3, 5, 11, 14, 20, 32, 52, 57, 70, 72, 81, 95, 114, 124, 231, 240, 273, 276, 287, 291, 371, 380, 441, 507, 528, 544, 573, 607, 629, 647, 672, 695, 716, 739, 828, 830, 832, 873, 1002, 1035, 1037, 1044, 1100, 1104, 1182, 1208, 1236, 1278, 1321, 1340, 1367, 1522
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OFFSET
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1,1
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COMMENTS
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Numbers k such that A001358(A001358(k)) + 1 = A001358(A001358(k+1)).
Numbers k such that A091022(k) + 1 = A091022(k+1).
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LINKS
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Table of n, a(n) for n=1..52.
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EXAMPLE
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3 is a term because semiprime(semiprime(3)) + 1 = 25 + 1 = semiprime(semiprime(3+1)).
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MAPLE
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A091022 := proc(n) A001358(A001358(n)) ; end proc: isA176658 := proc(n) A091022(n)+1 = A091022(n+1) ; end proc: for n from 1 to 1600 do if isA176658(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Apr 26 2010
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CROSSREFS
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Cf. A001358, A091022.
Sequence in context: A166564 A058595 A154773 * A086284 A136500 A024897
Adjacent sequences: A176655 A176656 A176657 * A176659 A176660 A176661
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KEYWORD
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nonn
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AUTHOR
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Juri-Stepan Gerasimov, Apr 23 2010
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EXTENSIONS
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Corrected (72 inserted, 85 replaced by 95, 124 inserted) and extended by R. J. Mathar, Apr 26 2010
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STATUS
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approved
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