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A203815 Primes which are the decimal concatenation of two squares in more than one way. 0
14449, 4651249, 14592449, 25281961, 64516961, 144552049, 4963984001, 10241442401, 121828921681, 1089936421201, 1589776384961, 4640334443681, 19713620187049, 25593280441009, 81105458016049, 121521961692601, 445309309225961 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A167535.

LINKS

Table of n, a(n) for n=1..17.

EXAMPLE

a(1) = 14449 = the concatenation of 12^2 and 7^2 and of 38^2 and 3^2.

a(5) = 64516961 = the concatenation of 8^2 and 719^2 and of 254^2 and 31^2.

MATHEMATICA

K[m_Integer, n_Integer] := n+m*10^IntegerLength[n]; k=-1; V={}; g=5000000; W={}; While[k<g, k++; m=2 k+1; n=0; While[n<2 g, n++; a=K[n^2, m^2]; If[a>10 (2 g)^2, n=2 g, If[PrimeQ[a], V={V, a}]]]]; V=Flatten[V]; W1=Sort[V]; W2=Union[V](*= A167535*); i=0; While[i<Length[W1]-1, i++; If[W1[[i+1]]==W1[[i]], W=Append[W, W1[[i]]]]]; Union[W]

CROSSREFS

Cf. A167535.

Sequence in context: A250960 A238060 A210050 * A076165 A234119 A253116

Adjacent sequences:  A203812 A203813 A203814 * A203816 A203817 A203818

KEYWORD

nonn,base

AUTHOR

Emmanuel Vantieghem, Jan 06 2012

STATUS

approved

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Last modified January 17 16:53 EST 2019. Contains 319235 sequences. (Running on oeis4.)