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A167412 Primes p such that sum of (digits^2) + 1 is prime. 2

%I #11 May 10 2019 22:11:50

%S 2,11,13,19,31,37,59,73,79,97,101,103,109,163,181,211,233,251,257,277,

%T 307,349,383,439,499,509,521,541,563,587,613,631,653,709,727,769,787,

%U 811,857,877,907,929,967,1009,1021,1063,1117,1151,1153,1171,1201,1223

%N Primes p such that sum of (digits^2) + 1 is prime.

%C 11 is a term because 1^2 + 1^2 + 1 = 3 (prime);

%C 163 is a term because 1^2 + 6^2 + 3^2 + 1 = 47;

%C 277 is a term because 2^2 + 7^2 + 7^2 + 1 = 103.

%H Vincenzo Librandi, <a href="/A167412/b167412.txt">Table of n, a(n) for n = 1..1300</a>

%p A003132 := proc(n) local d; add(d^2,d=convert(n,base,10)) ; end proc: A167412 := proc(n) local p; if n = 1 then 2; else p := nextprime(procname(n-1)) ; while not isprime(A003132(p)+1) do p := nextprime(p) ; end do ; return p end if ; end proc: seq(A167412(n),n=1..80) ; # _R. J. Mathar_, Nov 04 2009

%t Select[Prime[Range[2000]], PrimeQ[Total[IntegerDigits[#]^2] + 1]&] (* _Vincenzo Librandi_, Sep 25 2014 *)

%Y Cf. A167414.

%K nonn,base

%O 1,1

%A _Vincenzo Librandi_, Nov 03 2009

%E 2, 211, 233 inserted and more terms after 653 added by _R. J. Mathar_, Nov 04 2009

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)