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%I #9 Mar 27 2024 12:29:04
%S 4,8,12,18,18,22,26,36,32,36,40,54,46,50,95,56,75,62,66,70,93,76,145,
%T 82,86,114,92,96,100,132,106,110,273,116,153,122,126,240,132,174,138,
%U 142,146,192,152,290,158,162,213,168,172,176,231,182,455,188,192,252
%N Consider the triangle shown below in which the n-th row contains the n smallest terms in increasing order having a common factor > 1, the first term being the n-th composite number; sequence gives the last term of each row.
%C 4
%C 6 8
%C 8 10 12
%C 9 12 15 18
%C 10 12 14 16 18
%C 12 14 16 18 20 22
%C ...
%t A002808[n_] := Module[{resul, i}, i = 1; resul = 4; While[i < n, resul++; While[PrimeQ[resul], resul++]; i++]; Return[resul]];
%t A079775[n_] := Module[{a, anxt, atst }, a = {A002808[n]}; While[Length[a] < n, anxt = a[[-1]] + 1; atst = Append[a, anxt]; While[GCD @@ atst == 1, anxt++; atst = Append[a, anxt]]; a = Append[a, anxt]]; Return[a]];
%t A079774[n_] := A079775[n][[-1]];
%t Table[ A079774[n], {n, 1, 58}] (* _Jean-François Alcover_, Mar 27 2024, after _R. J. Mathar_ in A079775 *)
%Y Cf. A079775, A079776.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Jan 31 2003
%E Corrected and extended by _Frank Ellermann_, Jul 11 2003
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