A001573 Another approximation to A000084(n).

1, 2, 4, 9, 23, 63, 177, 514, 1527, 4625, 14230, 44357, 139779, 444558, 1425151, 4600339, 14939849, 48778197, 160019885, 527200711

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• more

Comments

Appears to have been calculated with very low precision. A093156 is a better version. - Pab Ter (pabrlos(AT)yahoo.com), May 11 2004

References

• J. Riordan and C. E. Shannon, The number of two-terminal series-parallel networks, J. Math. Phys., 21 (1942), 83-93. Reprinted in Claude Elwood Shannon: Collected Papers, edited by N. J. A. Sloane and A. D. Wyner, IEEE Press, NY, 1993, pp. 560-570.
• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• J. Riordan and C. E. Shannon, The number of two-terminal series-parallel networks (annotated scanned copy)

Crossrefs

Cf. A000084, A058585.