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 A063403 a(1) = 8, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1). 0
 8, 24, 46, 223, 1223, 11223, 87129, 189461, 414621, 2072003, 12072003, 34024001, 163920759, 354640253, 1074732999, 7377145687, 17377145687, 57053304579, 393145173803, 834736688841, 8062231035367, 26899299722333, 27745499695017 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..23. MATHEMATICA f[ n_Integer ] := (d = Divisors[ n ]; l = Length[ d ]; If[ EvenQ[ l ], ToExpression[ ToString[ d[[ l/2 ] ]] <> ToString[ d[[ l/2 + 1 ]] ]], ToExpression[ ToString[ d[[ l/2 + .5 ] ]] <> ToString[ d[[ l/2 + .5 ] ]] ]] ); NestList[ f, 8, 25 ] CROSSREFS Cf. A003681, A062094 and A062095. Sequence in context: A051062 A152531 A074348 * A355433 A348119 A306415 Adjacent sequences: A063400 A063401 A063402 * A063404 A063405 A063406 KEYWORD base,nonn AUTHOR Robert G. Wilson v, Aug 09 2001 STATUS approved

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Last modified June 13 02:31 EDT 2024. Contains 373366 sequences. (Running on oeis4.)