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A191401 k-almost primes which are digitally balanced in base 2 and have 2k digits in base 2, for some k >= 1. 0
2, 9, 10, 42, 44, 50, 52, 135, 150, 156, 184, 198, 204, 210, 225, 228, 232, 675, 684, 696, 728, 744, 752, 920, 944, 968, 976, 2484, 2544, 2646, 2673, 2744, 2772, 2835, 2904, 2928, 2992, 3132, 3150, 3192 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence contains all terms j of A031443 where A001222(j) = A070939(j)/2.

LINKS

Table of n, a(n) for n=1..40.

EXAMPLE

10=A031443(3) is in the sequence because it has 2 ones and 2 zeros in binary, and is a semiprime (A001358).

50=A031443(12) is in the sequence because it has 3 ones and 3 zeros in binary and is a 3-almost prime (A014612).

MAPLE

isA031443 := proc(n) local d2 ; d2 := nops(convert(n, base, 2)) ; return( 2*wt(n) = d2 ) ; end proc ;

isA191401 := proc(n) local k ; if isA031443(n) then k := nops(convert(n, base, 2))/2 ; return( numtheory[bigomega](n) = k ) ; else false; end if; end proc:

for n from 1 to 3200 do if isA191401(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Jun 08 2011

CROSSREFS

Cf. A031443.

Sequence in context: A179888 A073082 A300129 * A338997 A085069 A207670

Adjacent sequences:  A191398 A191399 A191400 * A191402 A191403 A191404

KEYWORD

nonn,base,less

AUTHOR

Juri-Stepan Gerasimov, Jun 01 2011

EXTENSIONS

Corrected by R. J. Mathar, Jun 08 2011

STATUS

approved

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Last modified September 28 19:16 EDT 2021. Contains 347717 sequences. (Running on oeis4.)