

A195039


23 times triangular numbers.


1



0, 23, 69, 138, 230, 345, 483, 644, 828, 1035, 1265, 1518, 1794, 2093, 2415, 2760, 3128, 3519, 3933, 4370, 4830, 5313, 5819, 6348, 6900, 7475, 8073, 8694, 9338, 10005, 10695, 11408, 12144, 12903, 13685, 14490, 15318, 16169, 17043, 17940, 18860
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OFFSET

0,2


COMMENTS

Related to the primitive Pythagorean triple [15, 8, 17].
Sequence found by reading the line from 0, in the direction 0, 23,..., and the same line from 0, in the direction 0, 69,..., in the Pythagorean spiral whose edges have length A195035 and whose vertices are the numbers A195036. This is the main diagonal of the square spiral.


LINKS



FORMULA

a(n) = (23*n^2 + 23*n)/2 = 23*n*(n+1)/2 = 23*A000217(n).
a(0)=0, a(1)=23, a(2)=69, a(n)=3*a(n1)3*a(n2)+a(n3).  Harvey P. Dale, Aug 28 2012


MATHEMATICA

23*Accumulate[Range[0, 40]] (* or *) LinearRecurrence[{3, 3, 1}, {0, 23, 69}, 50] (* Harvey P. Dale, Aug 28 2012 *)


PROG



CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



