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A316858 Triangle read by rows constructed from A090368 as sum of least prime factors. 1
6, 8, 8, 10, 10, 10, 6, 12, 12, 6, 14, 8, 14, 8, 14, 16, 16, 10, 10, 16, 16, 6, 18, 18, 6, 18, 18, 6, 20, 8, 20, 14, 14, 20, 8, 20, 22, 22, 10, 16, 22, 16, 10, 22, 22, 6, 24, 24, 6, 24, 24, 6, 24, 24, 6, 26, 8, 26, 20, 14, 26, 14, 20, 26, 8, 26, 8, 28, 10, 22, 28, 16, 16, 28, 22, 10, 28, 8 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The greatest number in row k is 2*k + 4, thus consecutive rows identify consecutive even numbers (sums of two primes).
To get the n-th row: copy (1...n) of A090368, reverse, and add together.
When primes meet primes we get the maximum values. When primes or prime factors meet prime factors, we get lesser values. (Spot checked. Still empirical.)
LINKS
EXAMPLE
Triangle begins:
{ 6}, <--- copy (1,1) of A090368, add together
{ 8, 8}, <--- copy (1,2) of A090368, reverse, and add together
{10, 10, 10}, <--- copy (1,3) of A090368, reverse, and add together
{ 6, 12, 12, 6},
{14, 8, 14, 8, 14},
{16, 16, 10, 10, 16, 16},
{ 6, 18, 18, 6, 18, 18, 6}, <=== differences from A316859 begin here
{20, 8, 20, 14, 14, 20, 8, 20},
{22, 22, 10, 16, 22, 16, 10, 22, 22},
{ 6, 24, 24, 6, 24, 24, 6, 24, 24, 6},
{26, 8, 26, 20, 14, 26, 14, 20, 26, 8, 26},
{ 8, 28, 10, 22, 28, 16, 16, 28, 22, 10, 28, 8}
MATHEMATICA
lpf[n_] := FactorInteger[2 n + 1][[1, 1]]; A090368 = Array[lpf, 12];
a = Flatten[Table[A090368[[1 ;; -n]] + Reverse[A090368[[1 ;; -n]]],
{n, Length[A090368], 1, -1}]];
CROSSREFS
Cf. A090368, A316859 (related triangle using gpfs).
Sequence in context: A229020 A113697 A154476 * A316859 A185200 A216275
KEYWORD
nonn,tabl
AUTHOR
Fred Daniel Kline, Jul 15 2018
STATUS
approved

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Last modified April 17 11:20 EDT 2024. Contains 371763 sequences. (Running on oeis4.)