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A089724 Numbers p satisfying the following conditions: p is a prime of form 10k+9 and the function f[p,7,10] applied to p is not greater than 5, where f[p,7,10]=10*fractionalpart[n/70]=1*.((n/70)-Floor[n/70]).

%I A089724 #12 Jun 04 2025 10:23:53
%S A089724 19,29,79,89,149,229,239,359,379,439,449,499,509,569,659,709,719,859,
%T A089724 919,929,1009,1069,1129,1279,1289,1409,1429,1489,1499,1549,1559,1619,
%U A089724 1699,1709,1759,1979,2039,2129,2179,2269,2339,2389,2399,2459,2539,2549
%N A089724 Numbers p satisfying the following conditions: p is a prime of form 10k+9 and the function f[p,7,10] applied to p is not greater than 5, where f[p,7,10]=10*fractionalpart[n/70]=1*.((n/70)-Floor[n/70]).
%t A089724 f[x_, d_, m_] := Mod[x/d, m]; (* or alternatively *) f[x_, d_, m_] := m*(x/(d*m)-Floor[x/(d*m)]); Do[If[PrimeQ[n]&&Equal[Mod[n, 10], 9]&&!Greater[f[n, 7, 10], 5], Print[n]], {n, 1, 1000}]
%Y A089724 Cf. A034433.
%K A089724 nonn
%O A089724 1,1
%A A089724 _Roger L. Bagula_, Jan 07 2004
%E A089724 Edited by _Labos Elemer_, Jan 24 2004