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A160792
Vertex number of a rectangular spiral related to prime numbers. The distances between nearest edges of the spiral that are parallel to the initial edge are the prime numbers, while the distances between nearest edges perpendicular to the initial edge are all one.
5
0, 1, 3, 5, 10, 13, 23, 27, 44, 49, 77, 83, 124, 131, 189, 197, 274, 283, 383, 393, 522, 533, 693, 705, 902, 915, 1153, 1167, 1448, 1463, 1791, 1807, 2188, 2205, 2645, 2663, 3164, 3183, 3751, 3771, 4410, 4431, 5143, 5165, 5956, 5979, 6853, 6877, 7840, 7865
OFFSET
0,3
COMMENTS
First differences give A160793. - Omar E. Pol, Oct 31 2011
LINKS
FORMULA
a(2n) = a(2n-1) + Sum_{j=1..n} prime(j); a(2n+1) = a(2n) + n + 1 for n >= 1. - Nathaniel Johnston, Jun 16 2011
MAPLE
A160792 := proc(n) option remember: if(n<=1)then return n: fi: if(n mod 2 = 0)then return procname(n-1)+add(ithprime(j), j=1..n/2): fi: return procname(n-1)+ceil(n/2): end: seq(A160792(n), n=0..49); # Nathaniel Johnston, Jun 16 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, May 29 2009
EXTENSIONS
Terms after a(10) and edited by Nathaniel Johnston, Jun 16 2011
STATUS
approved