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%I #16 Oct 04 2024 06:54:16
%S 1,10,12,16,18,21,27,29,34,38,43,49,54,56,61,65,67,72,76,81,89,92,94,
%T 98,100,102,106,108,112,126,130,136,138,148,150,156,162,166,172,178,
%U 180,190,192,196,198,209,221,225,227,231,237,239,249,255,261,267,269,275
%N Slowest increasing sequence where a(n)+(first digit of a(n)) is prime.
%H Robert Israel, <a href="/A107836/b107836.txt">Table of n, a(n) for n = 1..10000</a>
%e 1 + 1 = 2, which is prime; 10 + 1 = 11, which is prime; 12 + 1 = 13, which is prime; 16 + 1 = 17, which is prime; 18 + 1 = 19, which is prime; 21 + 2 = 23, which is prime; etc.
%p select(t -> isprime(t + floor(t/10^ilog10(t))), [$1..1000]); # _Robert Israel_, May 05 2020
%t Select[ Range[280], PrimeQ[ # + IntegerDigits[ # ][[1]]] &] (* _Robert G. Wilson v_, Jun 14 2005 *)
%o (Python)
%o from sympy import isprime
%o from itertools import count, islice
%o def agen(): # generator of terms
%o an = 0
%o while True:
%o an = next(k for k in count(an+1) if isprime(k + int(str(k)[0])))
%o yield an
%o print(list(islice(agen(), 58))) # _Michael S. Branicky_, Oct 03 2024
%K base,easy,nonn
%O 1,2
%A _Eric Angelini_, Jun 11 2005
%E Edited, corrected and extended by _Robert G. Wilson v_, Jun 14 2005