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A176292 Numbers k such that the prime factorizations of composite(k) and composite(k+1) have the same number of primes (including multiplicities). 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..59.

FORMULA

A001222(A002808(a(n))) = A001222(A002808(a(n)+1)).

MAPLE

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

CROSSREFS

Cf. A045920, A045939.

Sequence in context: A214641 A178598 A310675 * A050173 A078633 A190008

Adjacent sequences:  A176289 A176290 A176291 * A176293 A176294 A176295

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Apr 14 2010

EXTENSIONS

Corrected (86 replaced with 87, 89 removed, many terms after 92 replaced) by R. J. Mathar, Apr 20 2010

STATUS

approved

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Last modified October 26 14:28 EDT 2021. Contains 348267 sequences. (Running on oeis4.)