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A202450

Smallest k such that k*n!! +1 is an n-th power.

0, 1, 4, 21, 10, 69905, 2451, 1432028818087, 18166035, 72719023, 316138782904777094553940, 14747027341648947707567131341794256650861, 1801710500115237891740015, 37089922913701070144219234699757985931372002942260401897575393

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..13.

EXAMPLE

a(3) = 21 because 21*3!! + 1 = 21*3+1 = 64 = 4^3.

MATHEMATICA

a={}; Do[k = 2; While[ !IntegerQ[(k^n - 1)/n!!], k++ ]; AppendTo[a, (k^n-1)/n!!], {n, 0, 14}]; a

CROSSREFS

Cf. A006882.

Sequence in context: A225540 A128452 A333433 * A144292 A338421 A365101

Adjacent sequences: A202447 A202448 A202449 * A202451 A202452 A202453

KEYWORD

nonn

AUTHOR

Michel Lagneau, Dec 19 2011

STATUS

approved

URL: https://oeis.org/A202450

⇱ A202450 - OEIS