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 A182775 Giza nonprimes. 0
 1, 4, 6, 8, 9, 121, 232, 343, 454, 565, 676, 898, 12321, 23432, 45654, 56765, 67876, 78987, 1234321, 2345432, 3456543, 4567654, 5678765, 6789876, 123454321, 234565432, 456787654, 567898765, 12345654321, 23456765432, 45678987654 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS I propose the name Giza nonprimes. The total number of terms is 37. The largest is 12345678987654321 which is also the largest mountain number A134941. LINKS FORMULA A018252 INTERSECT A134810. EXAMPLE a(6)=121 is in the sequence because 121 is a nonprime number A018252 and 121 is also a Giza number A134810. The last six terms of this finite sequence are a(32) = 1234567654321 a(33) = 2345678765432 a(34) = 3456789876543 a(35) = 123456787654321 a(36) = 234567898765432 a(37) = 12345678987654321 Illustration of a(37) as a Giza nonprime: . . . . . . . . 9 . . . . . . . . . . . . . . . 8 . 8 . . . . . . . . . . . . . 7 . . . 7 . . . . . . . . . . . 6 . . . . . 6 . . . . . . . . . 5 . . . . . . . 5 . . . . . . . 4 . . . . . . . . . 4 . . . . . 3 . . . . . . . . . . . 3 . . . 2 . . . . . . . . . . . . . 2 . 1 . . . . . . . . . . . . . . . 1 MATHEMATICA Select[Union[FromDigits/@Select[Flatten[Table[Table[Join[Range[i, i+n], Reverse[ Most[ Range[ i, i+n]]]], {n, 0, 9}], {i, 9}], 1], Max[#]<10&]], !PrimeQ[#]&] (* Harvey P. Dale, Aug 23 2011 *) CROSSREFS Cf. A018252, A134810, A134811, A134941, A182776. Sequence in context: A202266 A232541 A076612 * A046354 A046357 A227947 Adjacent sequences:  A182772 A182773 A182774 * A182776 A182777 A182778 KEYWORD nonn,base,easy,fini AUTHOR Omar E. Pol, Dec 16 2010 STATUS approved

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Last modified October 23 11:48 EDT 2019. Contains 328345 sequences. (Running on oeis4.)