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A202450 Smallest k such that k*n!! +1 is an n-th power. 0
0, 1, 4, 21, 10, 69905, 2451, 1432028818087, 18166035, 72719023, 316138782904777094553940, 14747027341648947707567131341794256650861, 1801710500115237891740015, 37089922913701070144219234699757985931372002942260401897575393 (list; graph; refs; listen; history; text; internal format)
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 A329404 A076943

Adjacent sequences:  A202447 A202448 A202449 * A202451 A202452 A202453

KEYWORD

nonn

AUTHOR

Michel Lagneau, Dec 19 2011

STATUS

approved

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Last modified June 5 23:10 EDT 2020. Contains 334858 sequences. (Running on oeis4.)