

A090467


Numbers which are not regular figurative or polygonal numbers of order greater than 2. That is, numbers not of the form 1 + k*n(n1)/2  (n1)^2 where n >= 2 and k >= 2.


4



1, 2, 3, 4, 5, 7, 8, 11, 13, 14, 17, 19, 20, 23, 26, 29, 31, 32, 37, 38, 41, 43, 44, 47, 50, 53, 56, 59, 61, 62, 67, 68, 71, 73, 74, 77, 79, 80, 83, 86, 89, 97, 98, 101, 103, 104, 107, 109, 110, 113, 116, 119, 122, 127, 128, 131, 134, 137, 139, 140, 143, 146, 149, 151, 152
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OFFSET

1,2


REFERENCES

Albert H. Beiler, Recreations In The Theory Of Numbers, The Queen Of Mathematics Entertains, Dover, NY, 1964, pps. 185199.


LINKS

T. D. Noe, Table of n, a(n) for n=1..1000
Eric Weisstein's World of Mathematics, Figurate Number.
Index to sequences related to polygonal numbers


FORMULA

The nth kgonal number is 1 + k*n(n1)/2  (n1)^2 = A057145(k,n).


MATHEMATICA

Complement[ Table[i, {i, 300}], Take[ Union[ Flatten[ Table[1 + k*n(n  1)/2  (n  1)^2, {n, 3, 40}, {k, 3, 300}]]], 300]]


PROG

(PARI) isok(n) = (n < 3)  (vecsum(vector(n2, k, k+=2; ispolygonal(n, k))) == 1); \\ Michel Marcus, May 01 2016


CROSSREFS

Complement is A090466.
Sequence in context: A062890 A259626 A058586 * A177202 A053868 A241912
Adjacent sequences: A090464 A090465 A090466 * A090468 A090469 A090470


KEYWORD

easy,nonn


AUTHOR

Robert G. Wilson v, Dec 01 2003


EXTENSIONS

Verified by Don Reble, Mar 12 2006


STATUS

approved



