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.

A061597 Numbers whose sum of digits s equals its product of digits and s + 1 and s - 1 are both prime.

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%I A061597 #57 Dec 14 2024 15:13:05
%S A061597 4,6,22,123,132,213,231,312,321,111126,111162,111216,111261,111612,
%T A061597 111621,112116,112161,112611,116112,116121,116211,121116,121161,
%U A061597 121611,126111,161112,161121,161211,162111,211116,211161,211611,216111,261111,611112
%N A061597 Numbers whose sum of digits s equals its product of digits and s + 1 and s - 1 are both prime.
%H A061597 Harry J. Smith, <a href="/A061597/b061597.txt">Table of n, a(n) for n = 1..81</a>
%e A061597 22 belong to the sequence because (2*2)+1=5, (2*2)-1=3, (2+2)+1=5, (2+2)-1=3 and 2+2=2*2.
%o A061597 (PARI) isok(k) = my(d=digits(k), s=vecsum(d)); s == vecprod(d) && isprime(s+1) && isprime(s-1) \\ _Harry J. Smith_, Jul 25 2009
%Y A061597 Intersection of A034710 and A061596.
%K A061597 nonn,base
%O A061597 1,1
%A A061597 _Felice Russo_, May 22 2001
%E A061597 4 and 6 added by _Abdul Gaffar Khan_, Nov 29 2015