A227697 -id:A227697 - cp's OEIS frontend

A143850 Numbers of the form (p^2 + q^2)/2, for odd primes p and q.

9, 17, 25, 29, 37, 49, 65, 73, 85, 89, 97, 109, 121, 145, 149, 157, 169, 185, 193, 205, 229, 241, 265, 269, 277, 289, 325, 349, 361, 409, 425, 433, 445, 481, 485, 493, 505, 529, 541, 565, 601, 625, 661, 685, 689, 697, 709, 745, 769, 829, 841, 845, 853, 865

Offset: 1

T. D. Noe, Sep 03 2008

nonn

The primes in this sequence are listed in A103739.
a(n) mod 4 = 1. See A227697 for related sequence. - Richard R. Forberg, Sep 22 2013
The squares of primes in this sequence form the subsequence A001248 \ {4}. - Bernard Schott, Jul 09 2022

T. D. Noe, Table of n, a(n) for n = 1..1000

Cf. A001248, A045636, A103739, A227697.

Cf. A075892 (a subsequence).

Take[Union[Total[#]/2&/@(Tuples[Prime[Range[2,20]],2]^2)],60] (* Harvey P. Dale, Dec 28 2014 *)

list(lim)=my(v=List(), p2); lim\=1; if(lim<9, lim=8); forprime(p=3, sqrtint(2*lim-9), p2=p^2; forprime(q=3, min(sqrtint(2*lim-p2), p), listput(v, (p2+q^2)/2))); Set(v) \\ Charles R Greathouse IV, Feb 14 2017

A357439 Sums of squares of two odd primes.

Original entry on oeis.org

18, 34, 50, 58, 74, 98, 130, 146, 170, 178, 194, 218, 242, 290, 298, 314, 338, 370, 386, 410, 458, 482, 530, 538, 554, 578, 650, 698, 722, 818, 850, 866, 890, 962, 970, 986, 1010, 1058, 1082, 1130, 1202, 1250, 1322, 1370, 1378, 1394, 1418, 1490, 1538, 1658, 1682

Offset: 1

Giuseppe Melfi, Oct 06 2022

nonn

Although this is twice A143850, it is important enough to warrant an entry of it own. - N. J. A. Sloane, Oct 10 2022

Cf. A045636, A103739, A143850, A227697.

cp's OEIS Frontend

A143850 Numbers of the form (p^2 + q^2)/2, for odd primes p and q.

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