A135057 - OEIS

A135057

Largest semiprime whose prime factors add up to 10^n.

25, 2491, 249919, 24993439, 2499984871, 249999996751, 24999999992431, 2499999999940951, 249999999999995239, 24999999999999996031, 2499999999999999964279, 249999999999999999946639, 24999999999999999997538239, 2499999999999999999999854839, 249999999999999999999999946639

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OFFSET

1,1

LINKS

Lekraj Beedassy, Table of n, a(n) for n = 1..35

FORMULA

a(n) = A124450(n)*(10^n - A124550(n)) {= A137611(n)*A137612(n) for n>1}.

a(n) = 100^n/4-(A124049(n))^2. - Zak Seidov, Feb 15 2008

MATHEMATICA

s={}; f[{p_, e_}]:=e*p; Do[a=(10^n/2)^2; While[PrimeOmega[a]!=2||Total[f/@FactorInteger[a]]!=10^n, a=a-1]; AppendTo[s, a], {n, 11}]; s (* James C. McMahon, Apr 13 2025 *)

CROSSREFS

Sequence in context: A363192 A222276 A304323 * A324417 A167036 A342107

Adjacent sequences: A135054 A135055 A135056 * A135058 A135059 A135060

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Feb 11 2008

STATUS

approved