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

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, 41, 43, 47, 49, 53, 54, 59, 61, 64, 67, 71, 73, 75, 77, 79, 81, 83, 89, 97, 101, 103, 105, 107, 108, 109, 113, 121, 125, 127, 128, 131, 137, 139, 143, 149, 150, 151, 157, 162

Offset

1,2

Comments

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.

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Prog

(Haskell)
a133810 n = a133810_list !! (n-1)
a133810_list = 1 : filter f [2..] where
   f x = (and $ zipWith (<=) eps $ tail eps) &&
         (all (== 1) $ zipWith (-) (tail ips) ips)
     where ips = map a049084 $ a027748_row x
           eps = a124010_row x
-- Reinhard Zumkeller, Nov 07 2012

Crossrefs

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

Cf. A124010, A027748, A049084.

Sequence in context: A285710 A305669 A325364 * A176615 A291453 A185660

Adjacent sequences: A133807 A133808 A133809 * A133811 A133812 A133813

Keyword

nonn

Author

Olivier Gérard, Sep 23, 2007

Status

approved