A098515 Least m such that m and m+n are both products of exactly n primes counting multiplicity.

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

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