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A116935 Semiprimes (A001358) which are the concatenation of the numbers 1 through n for some n. 2
123, 1234, 1234567, 12345678910111213141516171819202122232425262728293031323334 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Next term has 185 digits, and it is thus too large to be included. It is equal to the concatenation of the first 97 integers. - Giovanni Resta, Jun 15 2016
LINKS
FORMULA
{A007908} intersect {A001358}.
EXAMPLE
a(1) = 123 = 3 * 41.
a(2) = 1234 = 2 * 617.
a(3) = 1234567 = 127 * 9721.
a(4) = 2 * 6172839455055606570758085909601061116212631364146515661667.
CROSSREFS
Sequence in context: A233119 A167231 A174173 * A265983 A103504 A324627
KEYWORD
base,nonn,less
AUTHOR
Jonathan Vos Post, Mar 20 2006
STATUS
approved

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Last modified May 24 07:02 EDT 2024. Contains 372772 sequences. (Running on oeis4.)