

A329026


Numbers k such that k = Product (p_j^e_j) = concatenation (pi(p_j)), where pi = A000720.


1




OFFSET

1,1


COMMENTS

Numbers k such that k equals concatenation of indices of distinct prime factors of k, in increasing order.
Fixed points of A329025.
a(5) > 2.4*10^11, if it exists.  Giovanni Resta, Nov 05 2019


LINKS

Table of n, a(n) for n=1..4.
Index entries for sequences computed from indices in prime factorization


EXAMPLE

2127 is a term because 2127 = 3 * 709 = prime(2) * prime(127) = concat(2, 127).


MATHEMATICA

a[n_] := FromDigits[Flatten@IntegerDigits@(PrimePi[#[[1]]] & /@ FactorInteger[n])]; Select[Range[2200], a[#] == # &]


CROSSREFS

Cf. A000720, A329025.
Sequence in context: A318298 A139310 A221819 * A307535 A180575 A115402
Adjacent sequences: A329023 A329024 A329025 * A329027 A329028 A329029


KEYWORD

nonn,base,more


AUTHOR

Ilya Gutkovskiy, Nov 02 2019


EXTENSIONS

a(4) from Giovanni Resta, Nov 04 2019


STATUS

approved



