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A039594 Positive a(n)-th hexagonal number ends with a(n). 1
1, 5, 6, 25, 26, 50, 51, 75, 76, 125, 376, 500, 501, 625, 876, 4376, 5000, 5001, 5625, 9376, 40625, 50000, 50001, 59376, 90625, 109376, 390625, 500000, 500001, 609376, 890625, 2109376, 2890625, 5000000, 5000001, 7109376, 7890625, 12890625, 37109376, 50000000, 50000001, 62890625, 87109376 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

k values for the sequence A038494.

REFERENCES

D. Wells, The Penguin Dictionary of Curious and Interesting Numbers, Penguin Book, p. 104.

C. Pickover, Computers and Imagination, 1991.

C. A. Pickover, Hexamorphic numbers, in Hexagonal cats Ch. 63 in Wonders of Numbers: Adventures in Mathematics, Mind, and Meaning, Oxford, England: Oxford University Press, pp. 154, 2001.

LINKS

Table of n, a(n) for n=1..43.

EXAMPLE

50 is included because the 50th hexagonal number ends with itself i.e. 49{50}.

PROG

(PARI) isok(n) = {my(m = n*(2*n-1)); (m - n) % 10^#Str(n) == 0; } \\ Michel Marcus, Sep 25 2015

CROSSREFS

Cf. A038494, A000384.

Sequence in context: A160529 A039572 A033042 * A137080 A025622 A116553

Adjacent sequences:  A039591 A039592 A039593 * A039595 A039596 A039597

KEYWORD

nonn,base

AUTHOR

Felice Russo

EXTENSIONS

More terms from Patrick De Geest, Jun 15 1999

More terms from Michel Marcus, Sep 25 2015

Definition corrected by Altug Alkan, Sep 25 2015

STATUS

approved

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Last modified February 23 04:57 EST 2018. Contains 299473 sequences. (Running on oeis4.)