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A176292
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Numbers k such that the prime factorizations of composite(k) and composite(k+1) have the same number of primes (including multiplicities).
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0
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1, 4, 7, 10, 12, 15, 17, 18, 21, 22, 25, 28, 29, 40, 47, 53, 61, 62, 64, 68, 69, 72, 85, 87, 90, 91, 93, 100, 102, 106, 107, 110, 112, 114, 116, 120, 125, 130, 131, 132, 133, 136, 151, 154, 155, 158, 165, 166, 169, 170, 179, 181, 190, 191, 198, 212, 221, 222, 223
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..59.
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FORMULA
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A001222(A002808(a(n))) = A001222(A002808(a(n)+1)).
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MAPLE
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A001222 := proc(n) numtheory[bigomega](n) ; end proc:
A002808 := proc(n) if n = 1 then return 4; else for a from procname(n-1)+1 do if not isprime(a) then return a; end if; end do; end if; end proc:
for n from 1 to 400 do if A001222(A002808(n)) = A001222(A002808(n+1)) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Apr 20 2010
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CROSSREFS
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Cf. A045920, A045939.
Sequence in context: A214641 A178598 A310675 * A050173 A078633 A190008
Adjacent sequences: A176289 A176290 A176291 * A176293 A176294 A176295
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KEYWORD
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nonn
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AUTHOR
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Juri-Stepan Gerasimov, Apr 14 2010
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EXTENSIONS
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Corrected (86 replaced with 87, 89 removed, many terms after 92 replaced) by R. J. Mathar, Apr 20 2010
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STATUS
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approved
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