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A030480 Primes with property that when squared all even digits occur together and all odd digits occur together. 2

%I #12 Oct 18 2023 10:04:29

%S 2,3,5,7,17,29,47,53,67,79,83,149,151,157,257,283,457,653,683,907,

%T 1429,1571,1693,1699,2017,2459,2467,2543,2609,2617,2843,2879,2909,

%U 2971,4759,5101,5179,5333,6653,6803,6947,6949,7759,8297,9091,9103

%N Primes with property that when squared all even digits occur together and all odd digits occur together.

%C Primes whose squares have at most one odd digit. - _Robert Israel_, Oct 17 2023

%H Robert Israel, <a href="/A030480/b030480.txt">Table of n, a(n) for n = 1..1000</a>

%p filter:= proc(n) local L;

%p if not isprime(n) then return false fi;

%p convert(convert(n^2,base,10)[2..-1] mod 2,set) = {0};

%p end proc:

%p filter(2):= true: filter(3):= true:

%p select(filter, [2,seq(i,i=3..10000,2)]); # _Robert Israel_, Oct 17 2023

%t With[{upto=10^4},Select[Prime[Range[upto]],Count[IntegerDigits[#^2],_?OddQ]<2&]] (* _Paolo Xausa_, Oct 18 2023 *)

%Y Cf. A030475, A030476.

%K nonn,base

%O 1,1

%A _Patrick De Geest_

%E Offset changed by _Robert Israel_, Oct 17 2023

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Last modified March 29 09:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)