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A034939
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a(n) is smallest number such that a(n)^2 + 1 is divisible by 5^n.
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5
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0, 2, 7, 57, 182, 1068, 1068, 32318, 110443, 280182, 3626068, 23157318, 120813568, 123327057, 1097376068, 11109655182, 49925501068, 355101282318, 355101282318, 3459595983307, 15613890344818, 110981321985443
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Moshe Levin, Table of n, a(n) for n = 0..100
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FORMULA
| a(n) = min(A048898(n), A048899(n)).
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MATHEMATICA
| b=2; n5=5; jo=Join[{0, b}, Table[n5=5*n5; b=PowerMod[b, 5, n5]; b=Min[b, n5-b], {99}]] (* Moshe Levin, Nov 04 2011 *)
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PROG
| (PARI) b(n)=if(n<2, 2, b(n-1)^5)%5^n; a(n)=min(b(n), 5^n-b(n))
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CROSSREFS
| Cf. A034935, A199206.
Sequence in context: A079410 A002658 A175818 * A048898 A034935 A178769
Adjacent sequences: A034936 A034937 A034938 * A034940 A034941 A034942
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KEYWORD
| nonn,nice,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Michael Somos
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