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A101081
Number of distinct prime factors of (prime p concatenated p times).
3
2, 2, 3, 3, 6, 6, 6, 3, 6, 8, 5, 7, 7, 8, 6, 6, 6, 10, 5, 5, 7, 10, 10, 9, 7, 7, 8, 11, 9, 8, 9, 14, 8
OFFSET
1,1
EXAMPLE
The number of distinct prime factors of 22 is 2.
The number of distinct prime factors of 333 is 2.
The number of distinct prime factors of 55555 is 3.
Then the number of distinct prime factors of 7777777 is 3.
a(16) comes from 53 * 107 * 1659431 * 1325815267337711173 * 47198858799491425660200071 * 9090909090909090909090909090909090909090909090909091. a(17) comes from 59 * 1889 * 2559647034361 * 1090805842068098677837 * 4411922770996074109644535362851087 * 4340876285657460212144534289928559826755746751. a(18) comes from 61 * 733 * 4637 * 81131 * 329401 * 974293 * 1360682471 * 106007173861643 * 7061709990156159479 * 11205222530116836855321528257890437575145023592596037161. Concerning a(19) = 67*(100^67-1)/99 = 67 * 493121 * 79863595778924342083 * 25648528130160606364784685146362888405160909090909090909090909090911655761903925151545569377605545379749607 (C107). - Robert G. Wilson v, Jan 27 2005
MATHEMATICA
f[n_] := Length[ FactorInteger[ FromDigits[ Flatten[ Table[ IntegerDigits[ Prime[n]], {Prime[n]}] ]]]]; Table[ f[n], {n, 15}] (* Robert G. Wilson v, Jan 27 2005 *)
Table[PrimeNu[FromDigits[Flatten[IntegerDigits/@PadRight[{}, p, p]]]], {p, Prime[Range[33]]}] (* Harvey P. Dale, Apr 06 2023 *)
CROSSREFS
Cf. A101459.
Sequence in context: A145787 A096111 A358337 * A373612 A147795 A258186
KEYWORD
nonn,base,more
AUTHOR
Parthasarathy Nambi, Jan 21 2005
EXTENSIONS
a(11)-a(15) from Ray Chandler, Jan 25 2005
a(16)-a(18) from Robert G. Wilson v, Jan 27 2005
Corrected and extended to a(33) by D. S. McNeil, Jan 07 2011
STATUS
approved