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A050676 Let b(n) = number of prime factors (with multiplicity) of concatenation of numbers from 1 to n; sequence gives smallest number m with b(m) = n. 1
1, 3, 2, 9, 8, 11, 28, 6, 26, 20 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..10.

P. De Geest, Normal Smarandache Concatenated Numbers, Prime factors from 1 up to n

C. Rivera, Primes by Listing

M. Fleuren, Factors and primes of Smarandache sequences.

M. Fleuren, Smarandache Factors and Reverse factors

MATHEMATICA

Join[{1}, Table[i=1; While[PrimeOmega[FromDigits[Flatten[IntegerDigits[Range[i]]]]]!=n, i++]; i, {n, 2, 10}]] (* Jayanta Basu, May 30 2013 *)

CROSSREFS

Cf. A007908, A050678, A046460.

Sequence in context: A201926 A288055 A081233 * A010372 A199455 A287768

Adjacent sequences:  A050673 A050674 A050675 * A050677 A050678 A050679

KEYWORD

nonn,base,hard

AUTHOR

Patrick De Geest, Aug 15 1999

STATUS

approved

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Last modified October 1 13:04 EDT 2020. Contains 337443 sequences. (Running on oeis4.)