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A036491 Transformation of A036490: 5^a*7^b*11^c -> 5^a*7^floor((b+2)/2)*11^c. 3

%I

%S 5,7,11,25,35,49,55,77,121,125,175,245,275,49,385,539,605,625,847,875,

%T 1225,1331,1375,245,1925,343,2695,3025,3125,539,4235,4375,5929,6125,

%U 6655,6875,1225,9317,9625,1715,13475,14641,15125,15625,343,2695,21175

%N Transformation of A036490: 5^a*7^b*11^c -> 5^a*7^floor((b+2)/2)*11^c.

%D G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976, p. 160.

%H Reinhard Zumkeller, <a href="/A036491/b036491.txt">Table of n, a(n) for n = 1..1000</a>

%t f[pp_(*primes*), max_(*maximum term*)] := Module[{a, aa, k, iter}, k = Length[pp]; aa = Array[a, k]; iter = Table[{a[j], 0, PowerExpand @ Log[pp[[j]], max/Times @@ (Take[pp, j-1]^Take[aa, j-1])]}, {j, 1, k}]; Table[Times @@ (pp^aa), Sequence @@ iter // Evaluate] // Flatten // Sort]; A036490 = f[{5, 7, 11}, 2*10^14] // Rest; a[n_] := (a0 = A036490[[n]]; b = Max[1, IntegerExponent[a0, 7]]; 7^(Floor[(b+2)/2]-b) * a0); Table[a[n], {n, 1, Length[A036490]}]; (* _Jean-François Alcover_, Sep 19 2012, updated Nov 12 2016 *)

%o (Haskell)

%o a036491 n = f z z where

%o f x y | x `mod` 2401 == 0 = f (x `div` 49) (y `div` 7)

%o | x `mod` 343 == 0 = y `div` 7

%o | otherwise = y

%o z = a036490 n

%o -- _Reinhard Zumkeller_, Feb 19 2013

%Y Cf. A036490, A036492.

%K nonn,easy,look

%O 1,1

%A _Olivier Gérard_

%E Offset corrected by _Reinhard Zumkeller_, Feb 19 2013

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Last modified April 26 08:44 EDT 2019. Contains 322472 sequences. (Running on oeis4.)