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 A081509 Primes of the form 1 + 2^k + 4^k + 6^k. 1
 13, 366993409, 789800591806169089, 8145612997113849913833354347764846494983651329 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(5) has 311 digits. - Harvey P. Dale, Mar 18 2019 Using the above, a(5) = 1 + 2^399 + 4^399 + 6^399. - David A. Corneth, Mar 18 2019 LINKS Table of n, a(n) for n=1..4. EXAMPLE n=1: 1 + 2 + 4 + 6 = 13 is prime. MATHEMATICA Do[s=1^w+2^w+4^w+6^w; If[IntegerQ[w/100], Print[{w}]]; If[PrimeQ[s], Print[{w, s}]], {w, 0, 1000}] Select[Table[1+2^n+4^n+6^n, {n, 60}], PrimeQ] (* Harvey P. Dale, Mar 18 2019 *) CROSSREFS Cf. A081510. Sequence in context: A158750 A145744 A174309 * A177224 A145234 A334634 Adjacent sequences: A081506 A081507 A081508 * A081510 A081511 A081512 KEYWORD nonn AUTHOR Labos Elemer, Apr 15 2003 STATUS approved

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Last modified June 13 23:50 EDT 2024. Contains 373391 sequences. (Running on oeis4.)