cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A000948 Number of free nonplanar polyenoids with n nodes and symmetry point group C_s.

Original entry on oeis.org

0, 3, 20, 99, 450, 1896, 7771, 30895, 121144, 468409, 1796584, 6841014, 25925062
Offset: 7

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Author

E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk)

Keywords

Links

Formula

a(n) = A000131(n+2) - A000941(n). - Sean A. Irvine, Oct 15 2015

Extensions

a(16)-a(19) and title improved by Sean A. Irvine, Oct 16 2015

A111198 Numbers k such that sequence A_k does not contain a perfect square.

Original entry on oeis.org

37, 40, 43, 57, 58, 101
Offset: 1

Views

Author

Zak Seidov, Oct 24 2005

Keywords

Comments

That is, the complete sequence A_k, not just the terms that are shown in the entry, does not contain a perfect square or the negative of a perfect square. (In particular, sequences containing 0 or 1 are excluded.)
No more terms up through 130. Does A000131 contain a perfect square?
I've checked A000131 up to a(25000) and can report that I found no perfect square. - Robert G. Wilson v, Jun 23 2014

Examples

			The first term, 37, refers to the sequence A000037, the nonsquares. All of A000001-A000036 contain obvious square terms.
The second term, 40, refers to A000040, the primes. Obviously any sequence which is a subset of the primes (e.g. A000043) also gives a term.

Links

Extensions

Let's have no more sequences of this type! - N. J. A. Sloane, Oct 23 2005
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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