cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A080102 Smallest prime power in all composite numbers between n-th prime and next prime, a(n) = 1 if no such prime power exists.

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%I A080102 #10 Mar 26 2025 08:28:31
%S A080102 4,1,8,1,16,1,1,25,1,32,1,1,1,49,1,1,64,1,1,1,81,1,1,1,1,1,1,1,121,
%T A080102 128,1,1,1,1,1,1,1,169,1,1,1,1,1,1,1,1,1,1,1,1,1,243,256,1,1,1,1,1,1,
%U A080102 289,1,1,1,1,1,1,343,1,1,1,361,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
%N A080102 Smallest prime power in all composite numbers between n-th prime and next prime, a(n) = 1 if no such prime power exists.
%H A080102 Amiram Eldar, <a href="/A080102/b080102.txt">Table of n, a(n) for n = 2..10000</a>
%e A080102 There are two prime powers between 32749 = A000040(3512) and 32771 = A000040(3513): 32761 = 181^2 and 32768 = 2^15, therefore a(3512) = 32761, A080103(3512) = 32768 and A080101(3512) = 2.
%t A080102 a[n_] := SelectFirst[Range[Prime[n] + 1, Prime[n + 1] - 1], PrimePowerQ, 1]; Array[a, 100, 2] (* _Amiram Eldar_, Mar 26 2025 *)
%Y A080102 Cf. A080101, A080103, A025475, A000961.
%K A080102 nonn
%O A080102 2,1
%A A080102 _Reinhard Zumkeller_, Jan 28 2003