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 A321284 a(n) = 2*(2^(35*3^n) + 1). 0
 68719476738, 81129638414606681695789005144066, 133499189745056880149688856635597007162669032647290798121690100488888732861290034376435130433538 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Terms are a practical numbers. a(3) has 285 digits. LINKS Table of n, a(n) for n=0..2. Li-Yuan Wang and Zhi-Wei Sun, On practical numbers of some special forms, arXiv preprint arXiv:1809.01532 [math.NT], 2018. FORMULA a(n) = A005843(A000079(35*A000244(n)) + 1). MAPLE a := n -> 2*(2^(35*3^n)+1): seq(a(n), n = 0 .. 5); MATHEMATICA a[n_]:=2*(2^(35*3^n)+1); Array[a, 5, 0] PROG (GAP) Flat(List([0..2], n->List([0..n], k->2*(2^(35*3^k)+1)))); (Magma) [2*(2^(35*3^n)+1): n in [0..5]]; (Maxima) a(n):=2*(2^(35*3^n)+1)\$ makelist(a(n), n, 0, 5); (PARI) a(n)=2*(2^(35*3^n)+1); tabl(nn) = for(n=0, nn, print1(a(n), ", ")); tabl(5) (Python) for n in range(5): print(2 * (2**(35 * 3**n) + 1), end=', ') CROSSREFS Cf. A005843, A000079, A000244, A005153 (practical number). Subsequence of A321308. Sequence in context: A017496 A017628 A139572 * A186095 A218397 A103617 Adjacent sequences: A321281 A321282 A321283 * A321285 A321286 A321287 KEYWORD nonn AUTHOR Stefano Spezia, Nov 02 2018 STATUS approved

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Last modified May 31 23:42 EDT 2023. Contains 363068 sequences. (Running on oeis4.)