cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A235053 Numbers k of the form p^2 + 1 (for prime p) where k^2 + 1 is also prime.

Original entry on oeis.org

10, 26, 170, 1850, 2210, 16130, 69170, 76730, 85850, 113570, 120410, 157610, 196250, 218090, 237170, 253010, 332930, 351650, 368450, 452930, 528530, 537290, 597530, 734450, 786770, 822650, 1329410, 2036330, 2211170
Offset: 1

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Author

Derek Orr, Jan 03 2014

Keywords

Comments

Except for 26, all numbers are divisible by 10 and the tens digit is an odd number.

Examples

			351650 = 593^2 + 1 (593 is prime) and 351650^2 + 1 is prime, so 351650 is a member of this sequence.
		

Crossrefs

Numbers in both A066872 and A005574.

Programs

  • Python
    import sympy
    from sympy import isprime
    {print(n**2+1) for n in range(10**7) if isprime(n) if isprime((n**2+1)**2+1)}