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A038494
Images of hexamorphic numbers: suppose k-th hexagonal number H(k) (A000384) ends in k; sequence gives positive values of H(k).
1
1, 45, 66, 1225, 1326, 4950, 5151, 11175, 11476, 31125, 282376, 499500, 501501, 780625, 1533876, 38294376, 49995000, 50015001, 63275625, 175809376, 3300740625, 4999950000, 5000150001, 7050959376, 16425690625, 23926109376
OFFSET
1,2
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.
EXAMPLE
45 is included because it is the 5th hexagonal number and it ends in 5.
MATHEMATICA
Select[Array[{PolygonalNumber[6, #], #} &, 10^6], FromDigits[Take[IntegerDigits[#], -IntegerLength@ #2]] == #2 & @@ # &][[All, 1]] (* Michael De Vlieger, Jun 30 2018 *)
PROG
(PARI) lista(nn) = {for (n=1, nn, m = n*(2*n-1); if ((m - n) % 10^#Str(n) == 0, print1(m, ", ")); ); } \\ Michel Marcus, Sep 25 2015
CROSSREFS
Sequence in context: A046426 A056776 A172466 * A026043 A372291 A330850
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
More terms from Patrick De Geest, Jun 15 1999
Name corrected by Robert Dawson, Jun 20 2018
STATUS
approved