A139582 Twice partition numbers.

2, 2, 4, 6, 10, 14, 22, 30, 44, 60, 84, 112, 154, 202, 270, 352, 462, 594, 770, 980, 1254, 1584, 2004, 2510, 3150, 3916, 4872, 6020, 7436, 9130, 11208, 13684, 16698, 20286, 24620, 29766, 35954, 43274, 52030, 62370, 74676, 89166, 106348, 126522, 150350, 178268, 211116, 249508, 294546, 347050, 408452

Offset: 0

Author

Omar E. Pol, May 14 2008

Keywords

• easy
• nonn

Comments

Except for the first term the number of segments needed to draw (on the infinite square grid) a minimalist diagram of regions and partitions of n. Therefore A000041(n) is also the number of pairs of orthogonal segments (L-shaped) in the same diagram (See links section). For the definition of "regions of n" see A206437. - Omar E. Pol, Oct 29 2012

Examples

			The number of partitions of 6 is 11, then a(6) = 2*11 = 22.
		

Links

• V. Modrak, D. Marton, A framework for generating and complexity assessment of assembly supply chains, in Nonlinear Science and Complexity (NSC), 2012 IEEE 4th International Conference on, Date of Conference: 6-11 Aug. 2012; Digital Object Identifier: 10.1109/NSC.2012.6304712. - From _N. J. A. Sloane_, Dec 27 2012
• V. Modrak, D. Marton, Development of Metrics and a Complexity Scale for the Topology of Assembly Supply Chains, Entropy 2013, 15, 4285-4299; doi:10.3390/e15104285.
• V. Modrak, D. Marton, Approaches to Defining and Measuring Assembly Supply Chain Complexity, Discontinuity and Complexity in Nonlinear Physical Systems, Vol. 6, 2014, pp. 192-213.
• V. Modrak, D. Marton, Configuration complexity assessment of convergent supply chain systems, International Journal of General Systems, Volume 43, Issue 5, 2014.
• Omar E. Pol, Illustration of initial terms of A139582 (n>=1) and of A066186

Crossrefs

Cf. A000041, A135010, A206437, A211026.

Programs

Mathematica

Array[2 PartitionsP@# &, 50, 0] (* Robert G. Wilson v, Feb 11 2018 *)

PARI

a(n) = 2*numbpart(n); \\ Michel Marcus, Feb 12 2018

Formula

a(n) = 2*A000041(n).

Extensions

More terms from Omar E. Pol, Feb 11 2018