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.
%I A344366 #57 Jun 07 2021 10:28:18 %S A344366 12,102,111,120,160,230,250,380,410,450,520,560,720,780,830,870,1002, %T A344366 1011,1020,1060,1100,1101,1110,1370,1640,1680,1910,1950,1970,1990, %U A344366 2030,2050,2340,2670,2920,3080,3170,3240,3420,3460,3550,3570,3710,3840,3860,4010 %N A344366 Integers k such that the sum of squares of digits of both k and k-1 are prime. %C A344366 Integers k such that k and k-1 are both in A108662. %C A344366 Terms are never prime. They cannot end in the digits 3,4,5,6,7,8,9. %C A344366 If k is a term, phi(k) is divisible by 4. %C A344366 The set of such numbers is infinite. %H A344366 Charles U. Lonappan, <a href="http://www.ijres.org/papers/Volume-9/Issue-1/D09011416.pdf">Consecutive natural numbers whose sum of squares of digits is prime</a>, International Journal of Research in Engineering and Science (IJRES), Volume 9 Issue 1 (2021) pp. 14-16. %e A344366 12 is in the sequence because the sum of squares of digits of 12 is 5 and that of 11 is 2, and both 5 and 2 are prime numbers. %t A344366 q[n_] := PrimeQ[Plus @@ (IntegerDigits[n]^2)]; Select[Range[2, 5000], q[#-1] && q[#] &] (* _Amiram Eldar_, May 19 2021 *) %o A344366 (PARI) isok(k) = isprime(norml2(digits(k-1))) && isprime(norml2(digits(k))); \\ _Michel Marcus_, May 24 2021 %Y A344366 Cf. A108662. %K A344366 nonn,base %O A344366 1,1 %A A344366 _Charles U. Lonappan_, May 19 2021