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 A110454 Largest composite number obtained by concatenation of parts of a distinct partition of n, or 0 if no such number exist. 1
 0, 0, 21, 0, 32, 321, 412, 512, 621, 4321, 5321, 6321, 7312, 8321, 54321, 64321, 74321, 84321, 94312, 432110, 654321, 754321, 854321, 954321, 5432110, 6432110, 7432110, 8432110, 9432110, 9654321, 65432110, 75432110, 85432110, 95432110, 96432110 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Conjecture a(n) = 0 only for n = 1, 2 and 4. LINKS EXAMPLE The partitions of 9 are 9, (8, 1), (7, 2), (6, 3), ...(6, 2, 1), (5, 3, 1), (4, 3, 2) etc. (432 is the largest number obtained as a concatenation of 4, 3, 2). MAPLE catL := proc(L) local a, i ; a := op(-1, L) ; for i from 2 to nops(L) do a := a*10^(max(1, ilog10(op(-i, L))+1))+op(-i, L) ; od: RETURN(a) ; end: A110454 := proc(n) local a, p, m, j ; a := 0 ; for p in combinat[partition](n) do if nops(p) = nops( convert(p, set)) then for j in combinat[permute](p) do m := catL(j) ; if ( m > 4 and not isprime(m) ) and ( m > a) then a := m ; fi ; od: fi ; od: RETURN(a) ; end: # R. J. Mathar, Feb 08 2008 CROSSREFS Sequence in context: A167263 A324685 A224114 * A265156 A040445 A040446 Adjacent sequences:  A110451 A110452 A110453 * A110455 A110456 A110457 KEYWORD base,nonn AUTHOR Amarnath Murthy, Aug 04 2005 EXTENSIONS a(9) corrected by James A. Sellers, Nov 18 2005 Corrected and extended by R. J. Mathar, Feb 08 2008 STATUS approved

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Last modified January 27 16:30 EST 2022. Contains 350608 sequences. (Running on oeis4.)