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A133810 Numbers that are primally tight and have weakly ascending powers. 5

%I #9 Jul 13 2013 12:03:30

%S 1,2,3,4,5,6,7,8,9,11,13,15,16,17,18,19,23,25,27,29,30,31,32,35,36,37,

%T 41,43,47,49,53,54,59,61,64,67,71,73,75,77,79,81,83,89,97,101,103,105,

%U 107,108,109,113,121,125,127,128,131,137,139,143,149,150,151,157,162

%N Numbers that are primally tight and have weakly ascending powers.

%C All numbers of the form p_1^k1*p_2^k2*...*p_n^k_n, where k1 <= k2 <= ... <= k_n and the p_i are n successive primes.

%H Reinhard Zumkeller, <a href="/A133810/b133810.txt">Table of n, a(n) for n = 1..10000</a>

%o (Haskell)

%o a133810 n = a133810_list !! (n-1)

%o a133810_list = 1 : filter f [2..] where

%o f x = (and $ zipWith (<=) eps $ tail eps) &&

%o (all (== 1) $ zipWith (-) (tail ips) ips)

%o where ips = map a049084 $ a027748_row x

%o eps = a124010_row x

%o -- _Reinhard Zumkeller_, Nov 07 2012

%Y Cf. A025487, A087980, A073491, A133808-A133813.

%Y Cf. A124010, A027748, A049084.

%K nonn

%O 1,2

%A _Olivier GĂ©rard_, Sep 23, 2007

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Last modified April 24 15:57 EDT 2024. Contains 371961 sequences. (Running on oeis4.)