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A098515 Least m such that m and m+n are both products of exactly n primes counting multiplicity. 4
1, 2, 4, 27, 36, 675, 810, 12393, 7552, 268992, 506240, 6436341, 2440692, 290698227, 455503986, 4897228800, 520575984, 519417147375, 124730265582, 8961777270765, 753891573760, 203558860750848, 51126160064490, 4021771417157632, 1305269217263592, 69131417822953472, 57710779788427264, 1838459534098563045, 63846774162325476 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

4=2*2 & 6=2*3; 27=3*3*3 & 30=2*3*5; 36=2*2*3*3 & 40=2*2*2*5; 675=3*3*3*5*5 & 680=2*2*2*5*17; 810=2*3*3*3*3*5 and 816=2*2*2*2*3*17; etc.

MATHEMATICA

f[n_Integer] := Plus @@ Transpose[FactorInteger[n]][[2]]; g[n_] := (k = 2^n; While[a = f[k]; b = f[k + n]; a != b || a != n, k++ ]; k); Do[ Print[ g[n]], {n, 12}]

CROSSREFS

Cf. A097978.

Cf. A097978, A135058.

Sequence in context: A095182 A104465 A175759 * A256451 A059719 A264930

Adjacent sequences:  A098512 A098513 A098514 * A098516 A098517 A098518

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Sep 11 2004

EXTENSIONS

More terms from David Wasserman, Feb 20 2008

STATUS

approved

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Last modified April 21 07:57 EDT 2021. Contains 343146 sequences. (Running on oeis4.)