A079774 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.

4, 8, 12, 18, 18, 22, 26, 36, 32, 36, 40, 54, 46, 50, 95, 56, 75, 62, 66, 70, 93, 76, 145, 82, 86, 114, 92, 96, 100, 132, 106, 110, 273, 116, 153, 122, 126, 240, 132, 174, 138, 142, 146, 192, 152, 290, 158, 162, 213, 168, 172, 176, 231, 182, 455, 188, 192, 252

Offset

1,1

Comments

4

6 8

8 10 12

9 12 15 18

10 12 14 16 18

12 14 16 18 20 22

...

Links

Table of n, a(n) for n=1..58.

Mathematica

A002808[n_] := Module[{resul, i}, i = 1; resul = 4; While[i < n, resul++; While[PrimeQ[resul], resul++]; i++]; Return[resul]];
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]];
A079774[n_] := A079775[n][[-1]];
Table[ A079774[n], {n, 1, 58}] (* Jean-François Alcover, Mar 27 2024, after R. J. Mathar in A079775 *)

Crossrefs

Cf. A079775, A079776.

Sequence in context: A098573 A092753 A276338 * A311555 A311556 A311557

Adjacent sequences: A079771 A079772 A079773 * A079775 A079776 A079777

Keyword

nonn

Author

Amarnath Murthy, Jan 31 2003

Extensions

Corrected and extended by Frank Ellermann, Jul 11 2003

Status

approved