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 A104242 Primes which are the concatenation of two consecutive square numbers. 4
 6481, 144169, 324361, 400441, 784841, 16001681, 23042401, 67246889, 77447921, 84648649, 92169409, 96049801, 1254412769, 1638416641, 1742417689, 1960019881, 2016420449, 4752447961, 5382454289, 5664457121, 5760058081, 6051661009 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The second prime in this sequence, 144169, arises in the theory of modular forms, as observed by Hecke. On page 671 of Hecke (1937), Hecke works out the cusp forms of weight 24 and observes that the Hecke operators have eigenfunctions with Fourier coefficients in the quadratic field of discriminant 144169. Thanks to Jerrold B. Tunnell for this comment. See also the articles by Hida and Zagier. N. J. A. Sloane, Sep 13 2014 REFERENCES E. Hecke, Über Modulfunktionen und die Dirichletschen Reihen mit Eulerscher Produktentwicklung, Math. Annalen, 114 (1937), 1-28; Werke pp. 644-671. See page 671. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 Haruzo Hida, Arithmetic of Weil numbers and Hecke fields. Don Zagier, Elliptic Modular Forms and Their Applications EXAMPLE The first term is 6481 which is a prime and is the concatenation of 64 and 81 which are two consecutive square numbers. MAPLE catn:= proc(a, b) 10^(1+ilog10(b))*a+b end proc: R:= NULL: count:= 0: for x from 2 by 2 while count < 100 do y:= catn(x^2, (x+1)^2); if isprime(y) then count:= count+1; R:= R, y; fi od: R; # Robert Israel, May 19 2020 PROG (Python) from sympy import isprime A104242_list = [] for n in range(1, 2000): ....x = int(str(n**2)+str((n+1)**2)) ....if isprime(x): ........A104242_list.append(x) # Chai Wah Wu, Sep 13 2014 CROSSREFS A090738 gives the numbers n such that a(n) = (n^2 concatenated with (n+1)^2) is prime. These are the primes in A246973. Cf. A104301, A246972. Sequence in context: A087351 A104343 A207837 * A031842 A028544 A237245 Adjacent sequences: A104239 A104240 A104241 * A104243 A104244 A104245 KEYWORD base,nonn AUTHOR Shyam Sunder Gupta, Apr 17 2005 STATUS approved

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Last modified March 31 11:51 EDT 2023. Contains 361648 sequences. (Running on oeis4.)