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A086924 Primes such that sum of the first and last digits is a square. 1
2, 13, 31, 79, 97, 103, 113, 163, 173, 193, 227, 257, 277, 311, 331, 613, 643, 653, 673, 683, 709, 719, 739, 769, 811, 821, 881, 907, 937, 947, 967, 977, 997, 1013, 1033, 1063, 1093, 1103, 1123, 1153, 1163, 1193, 1213, 1223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..44.

MATHEMATICA

fldsQ[n_]:=Module[{idn=IntegerDigits[n]}, IntegerQ[Sqrt[ idn[[1]] + idn[[-1]]]]]; Select[Prime[Range[200]], fldsQ] (* Harvey P. Dale, Aug 12 2017 *)

PROG

(PARI) okdigs(n) = digs = digits(n); issquare(digs[1]+digs[#digs]);

isok(n) = isprime(n) && okdigs(n); \\ Michel Marcus, Oct 05 2013

CROSSREFS

Cf. A088133, A088134, A088135, A088136.

Sequence in context: A156980 A158720 A108659 * A108660 A107132 A106959

Adjacent sequences:  A086921 A086922 A086923 * A086925 A086926 A086927

KEYWORD

easy,nonn,base

AUTHOR

Zak Seidov, Sep 20 2003

STATUS

approved

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Last modified September 23 01:32 EDT 2020. Contains 337291 sequences. (Running on oeis4.)