The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A167740 Primes that become squares when prefixed with a 7. 8
 29, 569, 1289, 7841, 62129, 306209, 436529, 502121, 634169, 667361, 935489, 1723961, 1927361, 2131049, 2437121, 2539289, 2948681, 3153809, 3564929, 4080449, 5116889, 5846681, 6160529, 6790169, 7316849, 7845329, 8269409, 8481881, 8694641, 8801129, 9869969 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi and David A. Corneth, Table of n, a(n) for n = 1..17124 (first 45 terms from Vincenzo Librandi) MATHEMATICA Select[Prime[Range[10000]], IntegerQ[Sqrt[FromDigits[Join[{7}, IntegerDigits[#]]]]]&] (* G. C. Greubel, Jun 23 2016 *) PROG (PARI) isok(n) = isprime(n) && issquare(n + 7*10^(length(Str(n)))) \\ Michel Marcus, Aug 05 2013 (PARI) \\ terms upto 10^n upto(n) = {my(sqrt71 = sqrt(7.1), sqrt80 = sqrt(8.0), r); for(k=2, n, for(j = ceil((sqrt71 * sqrt(10^k))), floor(sqrt80 * sqrt(10^k)), r = j^2%10^k; if(isprime(r), print1(r", "))))} \\ David A. Corneth, Jun 24 2016 CROSSREFS Cf. A167734, A167735, A167736, A167737, A167738, A167739, A167741. Sequence in context: A020978 A023948 A020974 * A158529 A020766 A069295 Adjacent sequences: A167737 A167738 A167739 * A167741 A167742 A167743 KEYWORD base,nonn AUTHOR Claudio Meller, Nov 10 2009 EXTENSIONS More terms from Michel Marcus, Aug 05 2013 Definition modified by Harvey P. Dale, Nov 12 2021 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 28 22:13 EDT 2024. Contains 372921 sequences. (Running on oeis4.)